OSX-1 FPSO Acquisition Update

7 October 2026

Rockhopper Exploration plc

("Rockhopper", the "Group" or the "Company")

OSX-1 FPSO Acquisition Update

Rockhopper Exploration plc (AIM: RKH), the oil and gas company with key interests in the North Falkland Basin, announces that, further to its announcement of 24 August 2026 regarding the acquisition of the OSX-1 floating production, storage and offloading vessel ("FPSO") for use in the accelerated development of the Central Development Area at Sea Lion, it has entered into an agreement to acquire its 35 per cent. pro rata participating interest in the OSX-1 FPSO (the "Subscription Agreement").

Pursuant to the Subscription Agreement, Rockhopper has agreed to subscribe for US$44.0 million of ordinary shares in a newly incorporated special purpose vehicle (the "SPV") that owns the OSX-1 FPSO. The subscription will be funded from the Company's existing cash resources. This subscription amount reflects the Company's 35 per cent. share of the previously disclosed aggregate acquisition cost of the OSX-1 FPSO, estimated at approximately US$125 million.

The SPV is a newly incorporated private company whose sole asset is the OSX-1 FPSO, and it has no material trading history or other business activities. Rockhopper is expected to incur net holding costs, attributable to Rockhopper's 35 per cent. pro rata participating interest, of approximately US$1.4 million per annum.

Enquiries:

Rockhopper Exploration plc

Sam Moody - Chief Executive Officer

Tel. +44 (0) 20 7390 0234 (via Vigo Consulting)

Canaccord Genuity Limited (NOMAD and Joint Broker)

Henry Fitzgerald-O'Connor/James Asensio/Charlie Hammond

Tel. +44 (0) 20 7523 8000

Peel Hunt LLP (Joint Broker)

Richard Crichton/Georgia Langoulant

Tel. +44 (0) 20 7418 8900

Vigo Consulting

Patrick d'Ancona/Ben Simons/Fiona Hetherington

Tel. +44 (0) 20 7390 0234

The information contained within this Announcement is deemed by Rockhopper Exploration plc to constitute inside information as stipulated under the Market Abuse Regulation (EU) No. 596/2014 as it forms part of UK law by virtue of the European Union (Withdrawal) Act 2018 ("MAR").

Notes to Editors

Rockhopper Exploration plc is a UK-based oil and gas exploration and production company with key interests in the Falkland Islands. The Company holds a 35% interest in licences in the North Falkland Basin, where it has sanctioned the development of the significant Sea Lion field which was originally discovered by the Company in 2010.

Rockhopper's shares are quoted on the AIM market of the London Stock Exchange under the ticker RKH.

For more information, visit the Company's website at www.rockhopperexploration.co.uk.