THIS ANNOUNCEMENT AND THE INFORMATION CONTAINED HEREIN, IS RESTRICTED AND IS NOT FOR RELEASE, PUBLICATION, DISTRIBUTION OR FORWARDING, IN WHOLE OR IN PART, DIRECTLY OR INDIRECTLY, IN OR INTO THE UNITED STATES, AUSTRALIA, CANADA, JAPAN, THE REPUBLIC OF SOUTH AFRICA OR ANY OTHER JURISDICTION IN WHICH SUCH RELEASE, PUBLICATION OR DISTRIBUTION WOULD BE UNLAWFUL.

THIS ANNOUNCEMENT IS FOR INFORMATION PURPOSES ONLY AND IS NOT AN OFFER OF SECURITIES IN ANY JURISDICTION.

29 December 2025

Rockhopper Exploration plc

("Rockhopper" or the "Company")

Publication of Open Offer Circular

Rockhopper Exploration plc (AIM: RKH), the oil and gas company with key interests in the North Falkland Basin, on 22 December 2025, announced the Financial Close on Sea Lion Project, Completion of Placing and Launch of Open Offer.

In respect of the Open Offer, a Circular containing its full details (together with an Open Offer Application Form for Qualifying Shareholders who hold their Ordinary Shares in certificated form), has today been posted to Shareholders who have elected to receive hard copies of shareholder documentation and published on the Company's website:

https://rockhopperexploration.co.uk/investors/shareholder-documents/  

Enquiries:

Rockhopper Exploration plc

Sam Moody - Chief Executive Officer

Tel. +44 (0)20 7390 0230 (via Vigo Consulting)

Canaccord Genuity Limited (Sole Bookrunner, NOMAD and Joint Broker)

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

Tel. +44 (0) 20 7523 8000

Peel Hunt LLP (Joint Broker, Lead Manager)

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

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.