Rockhopper Regulatory News (RKH)

Embargoed: 0700hrs 26 April 2011

Rockhopper Exploration plc

("Rockhopper" or the "Company")

Additional Drilling Slot

Rockhopper Exploration plc (AIM: RKH), the North Falkland Basin oil and gas exploration company, announces that it has entered into a further assignment agreement to secure an additional well slot on the Ocean Guardian drilling rig. Rockhopper now intends to utilise four well slots in succession.

Further information concerning the objectives and locations of the wells will be announced as appropriate.

Enquiries:

Rockhopper Exploration plc

Sam Moody - Chief Executive

Tel. +44 (0)20 7920 2340 (via M: Communications)

M: Communications

Patrick d'Ancona or Ben Simons

Tel. +44 (0)20 7920 2340

Canaccord Genuity Limited

Charles Berkeley / Henry Fitzgerald-O'Connor

Tel. +44 (0) 20 7050 6500

Notes to Editors

Rockhopper was established in February 2004 with a strategy to invest in and carry out an offshore oil exploration programme to the north of the Falkland Islands. The Company floated on AIM in August 2005 and holds a 100 per cent. interest in four offshore production licences: PL023, PL024, PL032 and PL033 which cover approximately 3,800 sq. km. Rockhopper has also farmed in (7.5% working interest) to licences PL003 and PL004, which are operated by Desire Petroleum. These licences have been granted by the Falkland Islands government.

An extensive work programme has been carried out over a number of years on the licences operated by Rockhopper. This has included 2D and 3D Seismic and Controlled Source Electromagnetic Mapping (CSEM). In February 2010, the Ocean Guardian drilling rig arrived in Falkland waters to carry out a multi-well drilling campaign. Rockhopper drilled an exploration well on its Sea Lion prospect during April and May 2010, the result of which was the first oil discovery and Contingent Oil Resource in the North Falkland Basin. The Sea Lion discovery was successfully tested during September 2010 and was the first oil to flow to surface in Falkland Islands waters. Rockhopper has contracted seismic vessels MV Polarcus Asima and Nadia to carry out a 3D seismic survey, beginning December 2010, over areas of licences PL024, PL032 and PL033 which were not previously defined by 3D, as well as adjacent areas.

Rockhopper is currently carrying out further drilling on Licence PL032.

Rockhopper Exploration plc www.rockhopperexploration.co.uk