Rockhopper Regulatory News (RKH)

Embargoed: 0700hrs 14 September 2011

Rockhopper Exploration plc

("Rockhopper" or the "Company")

14/10-7 well update

Rockhopper Exploration plc (AIM: RKH), the North Falkland Basin oil and gas exploration company, is pleased to provide an update on the 14/10-7 well.

·; Net pay 26m (85 feet)

net pay Sea Lion Main Complex (SLMC) 25m

net pay lower sands 1m

·; Gross reservoir SLMC 35m

·; Net to gross SLMC 72%

·; Reservoir quality in SLMC:

Average porosity 22%, maximum 27%

Average Sw 27%

Average permeability 70mD, maximum 230mD

·; No oil water contact was encountered

·; Results at upper end of expectations

14/10-7 is the fifth well to be drilled on the SLMC and was drilled 3.3km to the north west of the 14/10-2 discovery well to a total depth of 2696m.

The well was located close to the northern edge of the fan system in an area of relatively lower seismic amplitudes and thinner reservoir.

The well was successful, proving a high quality reservoir package and oil column. Wireline logging and formation testing indicate that 25m of net pay was encountered in the SLMC. A conventional core of 27m was cut and recovered from the SLMC reservoir.

The Company believes the well has de-risked the areas of relatively lower amplitudes within the SLMC and indicates that the edges of the sand lobes are likely to be below seismic tuning thickness.

Further work will be required to determine the extent of the SLMC SL20 lobe to the north of the well.

In addition, 1m of net pay was encountered in a thin lower sand with a deeper oil water contact than the SLMC, as in 10-2 and 10-5.

The well will now be plugged and abandoned as planned. On completion of operations on 14/10-7 the Ocean Guardian will move to drill well 14/10-N which is located approximately 4.1km south south east of the 14/10-2 discovery well. This well is designed to investigate reservoir and hydrocarbon presence within the SLMC in an area of relatively low amplitudes. 14/10-N is also an exploration well on both the Casper and Kermit oil prospects. A further announcement will be issued on spudding of the well.

Sam Moody, Chief Executive, commented:

"This is another excellent result with full credit going to our subsurface team for delivering Rockhopper's fifth successful well. We will shortly move to our next well which will target not only the SLMC but also Casper and Kermit prospects."

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 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

NB: This statement has been approved by the Company's geological staff who include David Bodecott (Exploration Director), who is a Member of Petroleum Exploration Society of Great Britain (PESGB) and the American Association of Petroleum Geologists (AAPG) with over 30 years of experience in petroleum exploration and management, for the purpose of the Guidance Note for Mining, Oil and Gas Companies issued by the London Stock Exchange in respect of AIM companies, which outline standards of disclosure for mineral projects.