0001193125-26-349155 Sample Contracts

ONE GAS, INC. $375,000,000 5.45% Senior Notes due 2036 Underwriting Agreement
Underwriting Agreement • August 13th, 2026 • ONE Gas, Inc. • Natural gas distribution • New York

ONE Gas, Inc., an Oklahoma corporation (the “Company”), proposes to issue and sell to the several Underwriters listed in Schedule 1 hereto (the “Underwriters”), for whom you are acting as representatives (the “Representatives”), $375,000,000 aggregate principal amount of its 5.45% Senior Notes due 2036 (the “Securities”). The Securities will be issued pursuant to an Indenture dated as of August 13, 2026 (the “Base Indenture”) between the Company, and U.S. Bank Trust Company, National Association, as trustee (the “Trustee”), as amended and supplemented by Supplemental Indenture No. 1 to be dated as of August 13, 2026 (the “Supplemental Indenture” and together with the Base Indenture, the “Indenture”).

ONE GAS, INC. and U.S. BANK TRUST COMPANY, NATIONAL ASSOCIATION, as Trustee INDENTURE Dated as of August 13, 2026
Indenture • August 13th, 2026 • ONE Gas, Inc. • Natural gas distribution • New York

INDENTURE, dated as of August 13, 2026 between ONE Gas, Inc., an Oklahoma corporation (herein called the “Company”), and U.S. Bank Trust Company, National Association, a national banking association, as trustee (herein called the “Trustee”).

ONE GAS, INC. SUPPLEMENTAL INDENTURE NO. 1 $375,000,000 5.45% Senior Notes due 2036
Supplemental Indenture • August 13th, 2026 • ONE Gas, Inc. • Natural gas distribution • New York

THIS SUPPLEMENTAL INDENTURE NO. 1, dated as of August 13, 2026 (this “Supplemental Indenture”), between ONE GAS, INC., an Oklahoma corporation (the “Company”), and U.S. BANK TRUST COMPANY, NATIONAL ASSOCIATION, a national banking association, as trustee (the “Trustee”).