Spinel-LiMn2O4 thin films were fabricated on stainless steel substrate by the r.f.-sputtering method. They were annealed within the range 400-700 degreesC for 1 h in O-2 and their electrochemical performance was compared to that of as-deposited film. The thin films were characterized by X-ray diffractometry and electron spectroscopy for chemical analysis (ESCA). Charge-discharge tests were carried out in an LiClO4/propylene carbonate solution. The films heat-treated at 400-700 degreesC exhibited excellent cyclability over a wide potential region from 2.0 to 4.3 V vs Li/Li+.