American Gas Association Financial ForumOrlando, Fla. | May 22, 2017

Pierce NortonPresident and Chief Executive Officer

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Statements contained in this presentation that include company expectations or predictions should be considered forward-looking statements that are covered by the safe harbor provisions of the Securities Act of 1933 and the Securities and Exchange Act of 1934.

It is important to note that the actual results could differ materially from those projected in such forward-looking statements.

For additional information that could cause actual results to differ materially from such forward-looking statements, refer to ONE Gas’ Securities and Exchange Commission filings.

All future cash dividends (declared or paid) discussed in this presentation are subject to the approval of the ONE Gas board of directors.

All references in this presentation to guidance are based on news releases issued on Jan. 17, 2017, Feb. 22, 2017 and May 1, 2017 and are not being updated or affirmed by this presentation.

Forward-Looking Statements

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• Company Overview

• Value Creation Strategy

• Financial Objectives

• Regulatory Update

• Q&A

What We’ll Cover

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• One of the largest publicly traded natural gas distribution companies

– 2.2 million customers

• 42,700 miles of distribution and transmission pipeline

• Estimated 2017 average rate base: $3.1 billion*

– 41% in Oklahoma– 32% in Kansas– 27% in Texas

• ~3,400 employees

Company Overview

Key Statistics

* Calculation consistent with utility ratemaking in each jurisdiction

72% market share

88% market share

13% market share

Value Creation Strategy

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Focused business strategy• Well-defined capital investment plan• 100% regulated natural gas distribution utility• One of the largest publicly traded natural gas distributors

Significant scale• High percentage of residential customers and fixed charges• 2.2 million customers• More than 70% of customers in metropolitan areas

Proximity to natural gas supply • Location to shale plays provides accessibility to affordable long-term reserves

Regulatory diversity • Three states; one with six jurisdictions• Average approximately 700,000 customers per state

Conservative financial profile • Commitment to “A-level” investment-grade credit ratings

Value Creation StrategySustainable Business

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73% 21%

6%

System Integrity Customer Growth Other/IT

Focused Business Strategy

Well-defined Capital Investment Plan

$ millions 2017 Guidance$ 255 System Integrity

$ 72 Customer Growth

$ 23 Other/IT

$ 350 Total Capital Expenditures

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Significant Scale

High Percentage of Residential Customers

*Based on 2016 annual results

* *

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Significant Scale

High Percentage of Fixed Charges

Kansas Oklahoma Texas Total

Fixed Charges – Sales customers* 55% 88% 70% 74%

Average Annual HeatingDegree Days – Normal 4,860 3,264 1,785 -

Weather Normalization 100% 100% 100% 100%

GovernanceKansas Corporation Commission (three commissioners appointed

by the governor to four-year staggered terms)

Oklahoma Corporation Commission (three

commissioners elected to six-year staggered terms)

“Home Rule” with 6**jurisdictions (Texas RailroadCommission has appellate

authority)

Note: Based on 2016 annual results* Fixed percentage of total net margin on natural gas sales** In 2016, Galveston and Port Arthur; El Paso, Dell City and Permian; Central and South Texas service areas were consolidated

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• Close proximity to significant natural gas reserves – 118 active rigs in Oklahoma*– 451 active rigs in Texas* – 64% of all rigs in U.S. operating in ONE Gas territories

• Leads to competitive natural gas delivered costs:– Cost of the commodity– Transportation costs– Storage fees

Proximity to Natural Gas Supply

Location Supports Sustainability

Topeka

ONE Gas Natural Gas Distribution AreasNatural Gas BasinsNatural Gas Shale Plays

* Source: Baker Hughes, as of May 15, 2017

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Natural Gas vs. Electricity

3-to-1 Average Advantage Continues in ONE Gas Territories

(1) Source: United States Energy Information Agency, www.eia.gov, for the twelve-months period ended December 31, 2016.(2) Represents the average delivered cost of natural gas to a residential customer, including the cost of the natural gas supplied, fixed customer charge, delivery charges and charges for riders, surcharges and other regulatory mechanisms associated with the services we provide, for the year ended December 31, 2016.(3) Calculated as the ratio of the natural gas price equivalent per dekatherm of the average retail price of electricity per kilowatt hour to the ONE Gas delivered average cost of natural gas per dekatherm.

$32.30 $29.51

$37.95

$10.97 $9.25 $10.07

2.9x 3.2x

3.8x

-

1.0

2.0

3.0

4.0

$-

$10

$20

$30

$40

$50

Texas Oklahoma Kansas

Natural gas price equivalent of electricity/Dth (1) OGS delivered cost of natural gas/Dth (2)

Natural gas advantage ratio (3)

Financial Objectives

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• Net income: range of $152-$162 million

• EPS: range of $2.87 - $3.07 • Rate base expected to grow an

average of approximately 5.0-5.5% per year between 2016-2021

• Expected average annual EPS growth of 5-7% between 2016 and 2021

2017 Guidance Announced January 17, 2017

$2.07 $2.24

$2.65

$2.97

$1.50

$2.00

$2.50

$3.00

$3.50

2014 2015 2016 2017G* 2018-2021

Diluted EPS

* Represents midpoint of guidance range

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• Dividend increased 20% for 2017• Quarterly dividend of 42 cents per

share, resulting in an annualized dividend of $1.68 per share*

• Target dividend payout ratio of 55-65% of net income

• Expected average annual dividend growth of 8-10% between 2016 and 2021

Growing Dividends

Building Shareholder Value

$0.84$1.20

$1.40 $1.68

2014** 2015 2016 2017G* 2018-2021

Dividends Declared

*Subject to quarterly board approval**In 2014, we paid dividends totaling $0.84 per share ($0.28 per share in each of our 2nd, 3rd and 4th quarters)

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• Majority of capital expenditures for safety, reliability and efficiency– System integrity and replacement– Efficiency

• Automated meter reading

• Operational efficiency efforts

– Government relocations– Fleet and facilities

• New service lines and main extensions for customer growth

• Information technology

$119 $131 $140 $154

2014 2015 2016 2017G 2018 - 2021

(in m

illion

s)

Depreciation

$350-$380/year

Capital Investment Drives Rate Base Growth

Capital Spending Exceeds Depreciation

$294 $302

Note: Capital expenditures include accruals and any adjustments in the year

$307$350

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352

245

259

123

180

131

2014

2015

2016

Pipeline Replacement

¹ Vintage Replacement Program ² Risk-Mitigation and Government Relocations

390

425

475

Investment Horizon

Long-Term Commitment to System Modernization

Pipeline replacement due to changes in state or federal regulations is not projected in this 5-year replacement estimate. Replacement mileage includes service lines, distribution mains and transmission pipelines. 1 The vintage asset replacement program includes: cast iron, wrought iron, unprotected bare steel, protected bare steel, vintage plastic. 2 Risk-mitigation pipeline replacement is due to asset operational performance, efficiency and government relocation projects.

(in m

iles) 750

1,100

2017-2021 Estimate

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• Leveraging technology to control expenses by:

– Increasing efficiency and optimizing processes

– Enhancing value for customers by more user-friendly and efficient websites, and applications

– Data-driven decision making

Focused on O&M expensesBuilding a Foundation for Long-term Affordability

$421 $414 $417 $419

2014* 2015 2016 2017G

(in m

illion

s)

O&M Expense

*In 2014, approximately $7 million incurred as a result of our separation from ONEOK

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• Dividends and capital expenditures primarily funded by cash flow from operations

• $700 million revolving credit facility

Asset removal costs$54

Sources Uses

(in m

illion

s)

Dividends$89

Capital expenditures

$350

Cash flow from operations*

$396

$493 $493

$97

2017 Cash Flow

Sources and Uses

* Before changes in working capital

Short-term debt and working capital changes

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• Strong liquidity position will support capital expenditure and working capital needs

– Stable operating cash flows

– $700 million revolving credit facility

– Commercial paper program

• Strong investment-grade credit ratings

Investment Grade

Commitment to Investment-Grade Ratings

Equity60%

Total Debt40%

Capital StructureAs of March 31, 2017

Rating Agency Rating Outlook

Moody’s A2 StableS&P A- Positive

Regulatory Update

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• Oklahoma Natural Gas– Performance-based rate structure (PBR) with a targeted ROE band of 9-10 percent that provides for annual

rate reviews between rate cases

• Kansas Gas Service– Gas System Reliability Surcharge (GSRS) – for incremental safety-related and government-mandated capital

investments made between rate cases

• Texas Gas Service– Gas Reliability Infrastructure Program (GRIP) for capital investments made between rate cases– Cost-of-service adjustments for capital investments and certain changes in operating expenses– Pipeline Integrity Testing (PIT) rider for related expenses– Rate cases as needed or required

Regulatory Mechanisms

Overview

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• Goal: Minimize the gap between allowed and actual returns

– 2017 ROE estimate: 8.1%– 2016 ROE achieved: 7.7%– 2015 ROE achieved: 7.4%– 2014 ROE achieved: 7.6%

Return on Equity

Minimize the Gap

7.6% 7.4% 7.7% 8.1%

2014 2015 2016 2017G

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2016

Regulatory Filing Timeline

Oklahoma & Kansas

2015 2016 2017 2018 2022

Filed general rate case application in July 2015, new rates approved and effective January 2016

Performance-based rate filings in March 2018, 2019 and 2020

ONG

Filed general rate case application May 2016, new rates approved and effective January 2017

KGS

GSRS filing annually in August, with new rates effective in January of the following yearRate cases as needed

2019 2020 2021

2015 2017 2018 20222019 2020 2021

General rate case application filing in June 2021, with new rates effective early 2022, if applicable

Performance-based rates change filing March 2017, no modification to base rates

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Jurisdiction Filing Highlights Status Increase in Base Rates

Rates Effective

Central Texas • GRIP for both incorporated and environs areas Filed March 3, 2017 $4.9 million TBD

West Texas • GRIP for both incorporated and environs areas• PIT filing for expenses incurred in the prior year

Filed March 15, 2017Filed February 21, 2017

$4.5 million$0.5 million

TBD

Gulf Coast • Rate case to adjust base rates• Consolidate Galveston and South Jefferson County

service areas

Approved $2.3 million May 2016

North Texas • Annual COSA filing to adjust base rates for incorporated cities

Approved $1.3 million July 2016

Regulatory Filing Timeline

Texas

Note: Consolidated jurisdictions in 2016 to six from 10 jurisdictions in Texas

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41%

32%

27%

2017 Estimated Rate BaseTotal: $3.1 billion*

Oklahoma Kansas Texas

Rate Base

Capital Investment Drives Rate Base Growth

* Estimated average rate base; calculation consistent with utility ratemaking in each jurisdiction

$2.3 $2.4$2.9 $3.1

2014 2015 2016 2017G

(in bi

llions

)

Rate Base

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• Well-defined capital investment plan with 70% targeted toward system integrity– Rate base expected to grow an average of 5.0-5.5% per year between 2016-2021

• Focus on controlling operating expenses• Minimize gap between actual and allowed returns

– Annual filings for rate adjustments between rate cases– File rate cases as warranted– Incremental regulated revenue

• Committed to stable and conservative financial profile– Expected average annual dividend growth of 8-10% between 2016 and 2021– Target dividend payout ratio of 55-65% of net income

Key Takeaways

Focused Strategy

Questions

Appendix

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Customer and Asset Mix

Key Statistics as of Dec. 31, 2016

Kansas Gas Service Oklahoma Natural Gas Texas Gas Service Total

Average Number of Customers 636,625 865,548 650,017 2,152,190

Average Number of Employees 1,000 1,200 800 3,400*

Distribution – Miles 11,600 18,500 10,100 40,200

Transmission – Miles 1,500 700 300 2,500

High-Density Cities Kansas City, Topeka, Wichita Oklahoma City, Tulsa Austin, El Paso 7 cities make up the

majority of customers

Percentage of Customers in Metropolitan Areas 58% 82% 76% 73%

Market Share - Customers Served 72% 88% 13%

* Includes corporate employees

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Capital Expenditures

By State

$136 $132 $134

$154

$57 $63 $64 $68

2014 2015 2016 2017G

(in m

illion

s)

Oklahoma

$82 $81 $85 $96

$41 $44 $47 $51

2014 2015 2016 2017G

Kansas

Depreciation

$76 $89 $88

$100

$21 $24 $29 $35

2014 2015 2016 2017G

Texas

Note: Capital expenditures include accruals and any adjustments in the year

2017: 2.3x depreciation 2017: 1.9x depreciation 2017: 2.9x depreciation

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Mechanism Oklahoma Kansas Texas*Performance-based rates X

Capital investments; safety-related riders X** X X

Weather normalization X X X

Purchased Gas Adjustment/Cost of Gas riders X X X

Energy efficiency/conservation programs X X

Pension and Other Post-Retirement Benefits Trackers X** X X

Cost of Service Adjustment X** X

Regulatory Constructs

By State

* Six jurisdictions in Texas; not all mechanisms apply to each jurisdiction** Incorporated in performance-based rates

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Regulatory Information

By State as of January 2017 - Authorized

Rate Base(in millions)

Rate Base per Customer

AuthorizedRate of Return

Authorized Return on

Equity

Oklahoma Natural Gas¹ $1,202 $1,396 7.31% 9-10%Kansas Gas Service² $925 $1,457 N/A N/ATexas Gas Service¹ $760 $1,177 7.5% 9.6%

¹ The rate base, authorized rate of return and authorized return on equity presented in this table are those from the last approved rate filings for each jurisdiction. These amounts are not necessarily indicative of current or future rate bases, rates of return or returns on equity.

² The most recent rate case was settled without a determination of rate base, return on equity or rate of return; rate base reflects Kansas Gas Service’s estimate of rate base contained within the settlement.

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Authorized Rate BaseHistorical by State at Year End

$938 $979

$1,202

2014 2015 2016

(in m

illion

s)

Oklahoma¹

$781 $826 $925

2014 2015 2016

Kansas²

$542 $639

$760

2014 2015 2016

Texas¹

¹ Rate bases presented in this table are those from the last approved rate filings for each jurisdiction. These amounts are not necessarily indicative of current or future rate bases. ² Last rate case was settled without a determination of rate base and includes the amounts included in the company’s filings; these amounts are not necessarily indicative of current or future rate base. 2014, 2015 and 2016 rate base reflects GSRS approvals.

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Highlights

Amount $29.995 million

Customer impact $2.96 per month increase for typical residential customer

Rate base $1.2 billion

Return on equity 9.5% (midpoint of allowed band)

Common equity ratio* 60.5%

Debt costs 3.95%

Other • Continuation of Performance Based Rate Change (PBR) plan• Regulatory asset for $2.4 million of separation costs

Oklahoma Natural Gas Rate Case

New Rates Effective January 2016

* The initial common equity ratio will be 60.5 percent, unchanged from the original filed request. For each future PBRC filing, the maximum allowed common equity ratio will decrease by 1 percent beginning with a 59 percent common equity ratio in the 2017 PBRC review of calendar year 2016, and ending with a 56 percent common equity ratio in the 2020 PBRC review of calendar year 2019.

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Highlights*Increase in base rates $15.5 million total increase, $8.1 million net increase (already recovering $7.4 million through GSRS)

Operating income impact Approximately $9.1 million in 2017

Other New rates effective January 1, 2017

Kansas Gas Service Rate Case

New Rates Effective November 2016

* Rate case settlement agreement is a “black box settlement,” meaning the parties agreed to a specific revenue number but no specific return on equity.

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Highlights

Increase in base rates $6.8 million; $3.4 million impact to operating income

Return on equity 9.5%

Common equity ratio 60.1%

Other • Approved consolidation of the South Texas service area with the Central Texas service area• November 2016: New rates effective for customers of incorporated cities of the former Central Texas service area and the

unincorporated areas of the new Central Texas consolidated area• January 2017: New rates effective for customers in incorporated areas of the new Central Texas consolidated service area

Texas Gas Service

Central Texas Service Area – New Rates Effective November 2016

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HighlightsIncrease in base rates $8.8 million; $7.6 million impact to operating income

Return on equity 9.5%

Common equity ratio 60.1%

Other • September 2016: Approved consolidation of the El Paso, Dell City and Permian service areas into a new West Texas service area

• October 2016: New rates went into effect except for the incorporated cities of the former Permian service area• December 2016: New rates went into effect for the incorporated cities in the former Permian service area

Texas Gas Service West Texas Service Area – New Rates Effective October 2016

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• Ongoing effort to replace aging assets– Replaced approximately 390 miles of distribution and transmission facilities in 2016

• Replaced approximately 22 miles of cast iron pipe in 2016

– Remaining 48 miles of cast iron pipe expected to be replaced by year end 2019

• Reduction in employee injuries of 30% in 2016 compared with 2015• Utilize peer-review safety process and employee training to promote consistent,

steady improvement in workplace safety

Safety and Environment

Operating Safely and Environmentally Responsibly

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2012 2013 2014 2015 2016

Customer Growth

Average Customer Count

2,114

(in th

ousa

nds)

2,1272,140

2,101

2,152

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200,000

400,000

600,000

800,000

1,000,000

1,200,000

1,400,000

1970 1972 1974 1976 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 2012 2014 2016

ONE Gas Major Metro U.S. Census County Population

Travis County, TX

El Paso County, TXOklahoma County, OK

Tulsa County, OKJohnson County, KS

Sedgwick County, KS

Service Territory Population Growth

1.45% CAGR (2000-2016)

* Source: U.S. Census Bureau, updated May 15, 2017

County 2000 Population 2016 Population % GrowthTravis, TX 811,776 1,199,323 48%El Paso, TX 679,568 837,918 23%Oklahoma, OK 660,581 782,970 19%Tulsa, OK 563,475 642,940 14%Johnson, KS 451,541 584,451 29%Sedgwick, KS 452,901 511,995 13%Total 3,619,842 4,559,597 26%

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Compressed Natural Gas (CNG)

Current Outlook

• Currently operate 26 fueling stations accessible to the public, 4 private stations

• Currently transporting supply to 66 retail and 49 private CNG stations

• Rebate program in Oklahoma; Austin, Texas• Industry

– Continued interest in CNG for transportation, particularly by fleet operators

– Tax incentives and rebates further contribute to positive economics

1.4 2.0 2.3 2.5

2013 2014 2015 2016

CNG Volume Dth – in millions

143 stations supplied129 stations supplied

115 stations supplied

100 stations supplied

Note: Updated as of March 31, 2017

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• Actual costs of the commodity, transportation and storage of natural gas are passed through to customers without markup– Natural gas used in operations is recovered in “Purchased Gas” or “Cost of Gas”

riders• Cost of Gas component of bad debts and hedging costs are included in cost of gas

• No direct commodity risk to ONE Gas divisions• Lease 50 Bcf of natural gas storage

Cost of Gas

Passed Through to Customers

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Cash Flow From Operations

Before Changes In Working Capital*

(Millions of dollars) 2017 Guidance 2016 Change

Net Income $ 153 $ 140 $ 13

Depreciation and amortization 155 144 11

Deferred taxes 73 87 (14)

Other 15 16 (1)

Cash flow from operations before changes in working capital $ 396 $ 387 $ 9

* Amounts shown are midpoints of ranges provided.

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ONE Gas has disclosed in this presentation cash flow from operations before changes in working capital, which is a non-GAAP financial measure. Cash flow from operations before changes in working capital is used as a measure of the company's financial performance. Cash flow from operations before changes in working capital is defined as net income adjusted for depreciation and amortization, deferred income taxes, and certain other noncash items.

The non-GAAP financial measure described above is useful to investors as an indicator of financial performance of the company's investments to generate cash flows sufficient to support our capital expenditure programs and pay dividends to our investors. ONE Gas cash flow from operations before changes in working capital should not be considered in isolation or as a substitute for net income or any other measure of financial performance presented in accordance with GAAP.

This non-GAAP financial measure excludes some, but not all, items that affect net income. Additionally, this calculation may not be comparable with similarly titled measures of other companies. A reconciliation of cash flow from operations before changes in working capital is included in this presentation.

Non-GAAP Information