Development of an improved water management membrane for a static vapor feed electrolyzer that produces sub-saturated H2 and O2 is proposed. This improved membrane can increase the performance and especially the durability of static vapor feed electrolyzers. Static vapor feed electrolyzers greatly simplify electrolyzer systems as they eliminate the need for water/gas phase separation, which is particularly challenging in a zero gravity environment. Maintaining water in the vapor phase greatly reduces membrane swelling which should increase durability. Finally, by keeping water in the vapor phase the MEA is not exposed to ion and other contaminants that are carried by a liquid water stream, further increasing durability and simplifying the system by reducing the need for ultra-pure water. The primary goal of this Phase II program then is to demonstrate the enhanced performance and durability of a static vapor feed electrolyzer utilizing an improved water management membrane.