Lithium-ion polymer cells are expected to provide power storage in microsatellites due to their high energy density, high voltage, and high flexibility in configuration. Our previous work demonstrated the excellent life performance of polymer electrolyte (PE)-type lithium-ion polymer cells in a vacuum. In this work, we determine whether this type of cell cycles normally in a space environment. We conducted endurance testing for gamma-ray radiation and vibration of the PE cells, simulating a microsatellite launch. The gamma-ray radiation testing revealed that these cells have excellent resistance to gamma-ray exposure in simulated low-Earth-orbit (LEO) and geostationary-Earth-orbit (GEO) environments. Vibration testing in an ultrahigh vacuum (10(-6) Pa) demonstrated that the cells could endure a microsatellite launch when fastened only with aluminum tape. During this testing, we did not detect any gas components associated with cell solvents. The promising results led us to conclude that PE cells can store power well for an LEO or GEO microsatellite. (c) 2005 The Electrochemical Society. [DOI: 10.1149/1.2131825] All rights reserved.