Solid polymer fuel cell (SPFC) systems are expected to see service in a wide variety of applications, including road vehicles, trains, ships, undersea power, and small scale stationary power generation. Each application brings unique requirements in terms of fuel, power, efficiency, volume and weight and, consequently, SPFC systems are expected to take a variety of forms. This paper reviews the development issues which must be resolved before SPFC systems can enter commercial service. It includes the results of system studies completed by Rolls-Royce and Associates during the last two years. Development priorities are highlighted, particularly for the stack and fuel processing system. Results of the testing of a novel compact fuel processing system are presented.