Business Responsibility and Sustainability Reporting for the FY 2025-26 which forms part of the Annual Report FY 2025-26 is attached herewith.

Hindustan Oil Exploration Company Limited ‘Lakshmi Chambers’, 192, St. Mary’s Road, Alwarpet, Chennai - 600 018. INDIA. : 91 (044) 66229000 ● Fax: 91 (044) 66229011 / 66229012 E-mail: contact@hoec.com ● Website: www.hoec.com CIN: L11100GJ1996PLC029880 September 2, 2026 By Online The Listing Department The Corporate Relationship Department National Stock Exchange of India Ltd., BSE Limited, “Exchange Plaza”, Bandra Kurla Complex, 1st Floor, P. Jeejeebhoy Towers, Bandra (East), Mumbai – 400 051 Dalal Street, Mumbai – 400 001 Stock Code: HINDOILEXP Stock Code: 500186 Dear Sir/Madam Sub: Submission of Business Responsibility and Sustainability Report for FY 2025–26 Pursuant to Regulation 34(2)(f) of the Securities and Exchange Board of India (Listing Obligations and Disclosures Requirements) Regulations, 2015, we are submitting herewith the Business Responsibility and Sustainability Report for Financial Year 2025–26, which forms part of the Annual Report for the Financial Year 2025–26. Kindly take our submission on record. Thanking you, Yours Sincerely, For Hindustan Oil Exploration Company Limited G. Josephin Daisy Company Secretary Encl.: a/a Registered Office: ‘HOEC HOUSE’, Tandalja Road, Off Old Padra Road, Vadodara - 390 020. INDIA. : 91 (0265) 2330766 ● E-mail: contact@hoec.com ● Website: www.hoec.com