AGM and Book Closure Notice is submitted 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: AGM and Book Closure Notice We wish to inform you that the 42nd Annual General Meeting (AGM) of the Members of Hindustan Oil Exploration Company Limited will be held on Friday, the 25th day of September 2026 at 11:00 A.M. through Video Conferencing (VC) / Other Audio Visual Means (OAVM), in accordance with the relevant circulars issued by the Ministry of Corporate Affairs and the Securities and Exchange Board of India. Pursuant to Regulation 34(1) of Securities Exchange Board of India (Listing Obligations and Disclosure Requirements) Regulations, 2015 (“SEBI Listing Regulations”), the Annual Report of the Company along with the Notice of AGM for the financial year 2025-26 is being sent through electronic mode to the Members who have registered their e-mail addresses with the Company/Depositories. Also, a letter providing the web link and exact path where complete details of the Annual Report of FY 2025-26 is available, is being sent to Members who have not registered their e-mail IDs. The Annual Report and the Notice of AGM is also uploaded on the Company’s website at https://hoec.com/annual-reports/ The details such as manner of registering / updating email addresses, casting vote through e-voting and attending the AGM through VC / OAVM has been set out in the Notice of the AGM. Pursuant to Regulation 42 of the SEBI (Listing Obligations and Disclosure Requirements) Regulations, 2015, the Register of Members & Share Transfer Books will remain closed from Saturday, September 19, 2026 to Friday, September 25, 2026 (both days inclusive), for purpose of the 42nd AGM. The Company has fixed Friday, September 18, 2026 as the “Cut-off Date” for the purpose of determining the members eligible to vote on the resolutions set out in the Notice of the AGM and to attend the AGM. The Company is availing e-voting services of Central Depository Services (India) Limited (CDSL). The remote e-voting period begins from Sunday, September 20, 2026 (9:00 a.m. IST) and ends on Thursday, September 24, 2026 (5:00 p.m. IST). We request you to kindly take the same on record. Yours Sincerely, For Hindustan Oil Exploration Company Limited G. Josephin Daisy Company Secretary & Compliance officer 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