The use of autonomous underwater systems, such as AUV, is currently limited by their on board energy supply. The emergence of a higher capacity power source could be a breakthrough that extends these technologies field of application. Since 2005, within the PACSM project1, fuel cell systems for underwater applications were studied. HELION, an AREVA Renewable subsidiary, dedicated to both PEM fuel cell and electrolyze systems development, has designed a fuel cell system adapted for AUV energy supply, for integration on IFREMER survey AUV, called IDEFX. This technology interest for underwater power source has already been proven by several experiments. For example, the URASHIMA propelled by a fuel cell system, performed 317 km longdistance continuous nonstop cruise. PACSM project objective is not only the development of a new prototype, but also to test its sea operational implementation. During sea experiments in October 2009, the AUV did 7 dives, with gas refill on the ship before each dive.