The proposed innovation is a passive, self-regulating, gravity-independent Advanced Product Water Removal (APWR) system for Polymer Electrolyte Membrane (PEM) primary fuel cell power plants that improves power plant efficiency and reliability, reduces reactant consumption, cost, weight and volume and simplifies the supporting system requirements in both near-term and advanced missions. Phase I program single cell test results demonstrated the function and feasibility of the innovation. The APWR power plant study demonstrated reliability, reactant saving, weight and volume saving and scalability improvements relative to both alkaline and conventional PEM power plants. Elimination of the pumps, rotating water separators and other components these conventional systems require saves weight, eliminates parasite power, saves the reactants to produce parasite power and improves reliability. APWR also simplifies the stack saving weight and volume and providing power plant scalability. APWR is based on PEM technology proven in automotive and commercial applications but not applied to space power plants: NASA need not carry the cost burden of developing this technology alone. The proposed Phase II program will demonstrate the viability of APWR technology at the stack level and establish an Engineering Data Base for power plant and full scale stack designs.