The hydrogen market is huge, currently about 10 million tons/year in the U.S. alone and a multi-billion dollar business. Industrial markets, such as refineries, ammonia production, chemical plants, etc, use most of the commercial quantities of hydrogen. Most of the hydrogen is either shipped to the end user via pipeline or trucked as compressed gas, at pressures of ~2,000 psi or greater. However, other applications for the hydrogen economy, especially vehicle refueling applications, require higher pressures, up to 12,000 psi. Successful development of efficient, high pressure water electrolysis systems is critically important in meeting these developing needs. It is anticipated that the worldwide combined industrial and emerging vehicle market for hydrogen will be >100 billion dollars. The successful development of an advanced passive liquid feed electrolyzer capable of operation at high pressure will be instrumental in supporting energy storage requirements for many NASA space missions. In particular, the ability to efficiently generate hydrogen and oxygen at high pressure allows the creation of high energy density systems for long-term space travel, Lunar and Mars bases. In addition, oxygen produced at high pressure can be used to meet space life support needs, including recharge of the EMU. Furthermore, successful development of high pressure cell technology can be instrumental in the creation of efficient hydrogen recovery systems that could result in substantial savings due to hydrogen loss resulting from cryogenic boil-off.