Regenerative processes for the air revitalization system of spacecraft atmosphere are essential for realization of long-term manned space missions. These processes include Oxygen (O2) Generation System (OGS) through water electrolysis. The authors have been studying O2 generation system of a new Solid Polymer Water Electrolyte (SPWE) with simplified cell structure since 1985. The initial study results until 1991 were presented in the 21st and the former International Conference on Environmental Systems shown in REFERENCE. This paper describes a follow-on study activity to OGS which focuses on the improvement of cell endurance performance and resource.