Li[Ni1/2Mn1/2]O-2 material was synthesized by ultrasonic spray pyrolysis method. Li[Ni1/2Mn1/2]O-2 was characterized by means of X-ray diffraction, charge/discharge cycling, and cyclic voltammetry. The discharge capacities of Li/Li[Ni1/2Mn1/2]O-2 cell at 30 and 55 degreesC slowly decreased with cycling and remained at 166 and 175 mAh/g after 50 cycles, which are 99 and 94% of initial capacities, respectively. The cyclic voltammogram studies of the Li[Ni1/2Mn1/2]O-2 electrode showed only one redox peak. This phenomenon might be related to the initial activation process and/or stabilization of Li[Ni1/2Mn1/2]O-2 electrode.