Rockhopper Regulatory News (RKH)

19 May 2015

Rockhopper Exploration plc

("Rockhopper" or the "Company")

Operations Update - Isobel Deep & Mediterranean

Rockhopper Exploration plc (AIM: RKH), the oil and gas exploration and production company with interests in the North Falkland Basin and the Greater Mediterranean region, is pleased to provide the following update ahead of the Company's AGM today in relation to the Isobel Deep Well and its Mediterranean operations.

Isobel Deep (Rockhopper 24%)

Following the penetration of a sand interval with suspected elevated formation pressure and oil shows, the operator has decided to set a cement plug over this interval and run the contingent 9 5/8" casing string in the shale section above, prior to drilling through the prognosed Isobel reservoir interval to the well TD (Total Depth).

The contingent casing string will enable additional flexibility while drilling and evaluating the target formation. This scenario had been anticipated and the additional 9 5/8" casing is already on the rig.

The presence of oil shows is not necessarily indicative of net pay and conclusive results for the well will not be available until drilling operations have been completed and logging data collected.

A further announcement on the results of the well will now be likely in early June.

Mediterranean

Guendalina (Rockhopper 20%)

A planned acid wash on the short string has been completed and has resulted in a gross production increase from 18k scm/d (thousand standard cubic metres per day) to 75k scm/d from that string. Overall gross production from Guendalina is currently approximately 190k scm/d ( or c.38k scm/d net to Rockhopper equivalent to approximately 223 boe/d (barrels of oil equivalent)) The planned sidetrack to the GUE2 well at Guendalina is due to take place during the summer of 2015.

Ombrina Mare (Rockhopper 100%)

The Environmental Impact Assessment ("EIA") of the Ombrina Mare Field Development Plan ("FDP") has been approved by the Minister for the Environment. The approval decree includes the 'Autorizzazione Integrata Ambientale' (Integrated Environmental Authorisation) ("AIA"). The decree now needs to be countersigned both by the Ministry of Cultural Heritage and then the Ministry of Economic Development in order for the Minister to be in a position to award the Field Production Concession.

Civita (Rockhopper 100%)

Development remains on track with construction having commenced. First gas is expected by the end of 2015.

The AGM presentation will be made available on the company web site later today.

For further information, please contact:

Rockhopper Exploration plc

Tel: (via Vigo Communications) - 020 7016 9571

Sam Moody - Chief Executive

Fiona MacAulay - Chief Operating Officer

Stewart MacDonald - Chief Financial Officer

Canaccord Genuity Limited (NOMAD and Joint Broker)

Tel: 020 7523 8000

Henry Fitzgerald-O'Connor

Liberum Capital (Joint Broker)

Tel: 020 3100 2227

Clayton Bush

Vigo Communications

Tel: 020 7016 9571

Peter Reilly

Patrick d'Ancona

Note regarding Rockhopper oil and gas disclosure

This announcement has been approved by Rockhopper's geological staff who include Fiona MacAulay (Chief Operating Officer), who is a Fellow of the Geological Society of London and a Member of the Petroleum Exploration Society of Great Britain and American Association of Petroleum Geologists with over 25 years of experience in petroleum exploration and management, and who is the qualified person as defined in the Guidance Note for Mining, Oil and Gas Companies issued by the London Stock Exchange in respect of AIM companies. In compiling its resource estimates, Rockhopper has used the definitions and guidelines as set forth in the 2007 Petroleum Resources Management System approved by the Society of Petroleum Engineers.