Rockhopper Regulatory News (RKH)

Embargoed: 0700hrs 17 October 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 using the Ocean Guardian drilling rig.

Rockhopper intends to utilise the additional well slot to drill a well on the north-western acreage of licence PL004, which the Company believes contains the extension to the Sea Lion field and has farmed-in with operatorship, subject to all regulatory consents, to earn an aggregate 60% interest. The well will be located in "Area 1" of the proposed farm in area, which will become known as licence PL004b once all regulatory consents are obtained.

Prior to drilling the well in "Area 1", Rockhopper will shortly drill well 14/10-9, the eighth well on the Sea Lion feature in licence PL032 (100% Rockhopper) and a further announcement will be made on spudding of this well.

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. As well as its own licences Rockhopper has also farmed in (7.5% earned interest) to licences PL003 and PL004, which are operated by Desire Petroleum. In addition to the original farm-in, and in consideration for paying the full cost of the drilling of one well on the north-western acreage of licence PL004, known as Area 1, which Rockhopper believes contains the extension to the Sea Lion field and the western part of the "Beverley" prospect, Rockhopper has farmed-in with operatorship and an aggregate 60% interest in Area 1. Rockhopper has further farmed into the north-eastern part of licence PL004 known as Area 2, which the Company believes contains the "Jayne" prospect and the eastern part of the "Beverley" prospect, with an aggregate 25% interest. The farm-in to Area 1 and Area 2 on licence PL004 remains subject to approval from 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 June 2011 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 a 3D seismic survey over areas of licences PL024, PL032 and PL033 which were not previously defined by 3D, as well as adjacent areas. Data over the southern portion of licences PL032 and PL033 has been fast track processed and an initial interpretation has now been completed. The balance of the newly acquired 3D seismic data is still being processed and the Company expects it will be available for interpretation before the end of 2011.

Rockhopper Exploration plc www.rockhopperexploration.co.uk