Rockhopper Regulatory News (RKH)

Embargoed: 0700hrs 18 April 2011

Rockhopper Exploration plc

("Rockhopper")

Ninky 14/15-3 exploration well result

Rockhopper Exploration plc (AIM: RKH), the North Falkland Basin oil and gas exploration company, notes the announcement by Desire Petroleum plc (the "Operator") regarding the 14/15-3 exploration well in which Rockhopper has a 7.5% interest:

14/15-3 well to be plugged and abandoned with oil shows

The Operator announced that the 14/15-3 well on the Ninky prospect has reached a total depth of 2620 metres in the Barremian source rock interval and provided the following update:

Ninky Well Results

Based on drilling and wireline logging, the well encountered two sand-prone sections in the Upper and Middle F2 intervals, which were the primary targets (2323 metres to 2334 metres and 2365 metres to 2389 metres). The sands have a combined gross thickness of 35 metres and oil shows were encountered throughout both intervals while drilling. The reservoir quality is generally poor having only 5.6 metres of net reservoir with an average porosity of 13%. A thin interval of around 1.2 metres at the top of the Middle F2 zone is interpreted to be oil bearing from log analysis.

Wireline formation pressure measurements were attempted, but no valid pressures were obtained, indicating that the reservoirs are low permeability at this location. As a result no wireline sampling was attempted. The depositional model suggests these sands are sourced from the east and therefore better reservoir quality may be expected downdip. In addition, there are indications from seismic of further sands along strike on the Ninky structural high, which were not penetrated in this well. These opportunities will be evaluated with the new 3D seismic as part of the Operator's prospect inventory update.

Operations on the Ninky well will now be completed and the well will be plugged and abandoned.

Upon completion of operations on the Ninky well, the Ocean Guardian drilling rig will return to Rockhopper. Rockhopper will drill a minimum of 3 additional wells using the Ocean Guardian drilling unit. Rockhopper's next well is planned to be located near to the 14/10-2 discovery well. Specialist flow test equipment is due to be in the Islands in early May and Rockhopper intends to flow test the well if appropriate using this equipment to obtain a greater understanding than was possible during the test of well 14/10-2.

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 contracted seismic vessels MV Polarcus Asima and Nadia to carry out 3D seismic surveys, beginning December 2010, over areas of licences PL024, PL032 and PL033 which were not previously defined by 3D, as well as adjacent areas.

Rockhopper Exploration plc www.rockhopperexploration.co.uk