NASA has a defined need for energy dense and highly efficient energy storage and power delivery systems for future space missions. Compared to other fuel cell technologies, solid oxide fuel cell (SOFC) based systems are better suited to meeting NASA's efficiency targets while operating directly on methane and oxygen reactants. SOFC power systems for lunar landers and other exploration vehicles are an ideal application for this technology, as well as for power generation on the moon or on Mars. NexTech Materials has established SOFC technology that offers high power density with direct internal fuel reforming and high single-pass fuel utilization, making it uniquely suited for achieving NASA's performance and efficiency requirements. In Phase I of this project, NexTech designed a methane/oxygen SOFC system and established a process model, designed the stack and hot box for this system, and completed testing to validate that the target efficiency of 70 percent was achievable. In Phase II of this project, NexTech will specify and source all system components, build a three-dimensional CAD model of the methane/oxygen SOFC system, build and test 1-kW scale stacks of the Phase I design, demonstrate 70 percent electrical efficiency in a stack with only methane and oxygen reactant feeds, and evaluate long term durability and thermal cycling capability of the stack.