A hybrid propulsion system for torpedo propulsion applications was developed. The hybrid system utilizes a solid oxide fuel cell (SOFC) to provide low power propulsion and hotel loads supplemented by a high power turbine for high speed pursuit, with both systems using common fuel and oxidant sources. A solid LiCl04 oxidant source was investigated. Individual subsystems including the SOFC stack and LiCl04 oxidant source were physically tested. Trade studies were performed comparing various fuel, oxidant, low power, and high power sources, based on testing performance of the subsystems. The SOFC low power system was demonstrated to provide the longest low power range while maintaining the necessary high power reserve for target pursuit.