NASA uses a number of water electrolysis units for generating oxygen and hydrogen gas for space applications. These missions range from generating propellants to supplying oxygen to crew and habitat. Consequently, the electrolyzer systems employ a variety of designs and system approaches that can generate high pressures or product gases with varying degrees of moisture, however, most of these approaches result in heavy and bulky systems. A new water electrolyzer was developed by MicroCell Technologies that allows pressurized gas to be generated in a lightweight and compact design. In a Phase I SBIR program, we demonstrated the feasibility of the electrolyzer to generate pressurized oxygen and hydrogen gas in a compact and lightweight electrolyzer design that can operate in a passive mode without requiring water pumps. Based on these results, we propose to scale the process in a Phase II program to a rate of 0.5 kg O2/hr in a device with a mass of 1000 g and a volume of 300 cc. This translates into high power densities of 6 kW/kg and 18 kW/liter, competitive metrics for an electrolyzer that can also generate high pressure to 2000 psi in a passive balance of plant approach.