Giner, Inc. has developed an advanced high pressure electrochemical oxygen concentrator (EOC) that offers a simple alternative to the use of pressure swing adsorption (PSA) systems to generate high pressure oxygen for the International Space Station (ISS) and future human space flight applications. The high pressure EOC is based on proven electrolyzer technology demonstrated at Giner and delivers a continuous stream of dry oxygen with a highly controllable oxygen pressure (0-3600 psi) by feeding a low pressure humidified oxygen stream into the cathode side of the stack where oxygen is consumed. The generation of pure oxygen at 3600 psig is particularly applicable for filling tanks used for extravehicular activity (EVA). The benefits of using this technology rather than a standard high or large pressure differential electrolyzer stack include: 1.) significantly reduced membrane degradation resulting in an improvement in stack lifetime, 2.) increased safety as there is no risk of producing a combustible gas mixture in the event of gas crossover through the MEA, and 3.) simplified balance of plant (BOP) for the reason that typical liquid cathode feed electrolyzer stacks require sophisticated water management. Giner further simplified the high pressure EOC BOP by integrating a low pressure static vapor feed electrolyzer (SVFE) into a shared-end-plate stack.