Abstract. A microelectrode technique was applied to investigate the electrochemical properties of LiMn2O4 particles at elevated temperatures. Cyclic voltammograms of LiMn2O4 were measured after the particles were exposed to the electrolytes. This technique results in rapid and precise evaluation of the redox behavior of the materials. A significant capacity fading was observed in 1M LiPF6/EC+PC electrolytic solution, which indicates that both LiMn2O4 and LiPF6 participate in the reaction to produce an inert material on the particle surface. Next, the capacity fading for two different BET surface area particles were compared using 1M LiPF6/EC+PC at 50C. The reaction was found not to be controlled by the surface area. Finally, a Li1.1Mn1.9O4 particle was employed. The fading in discharge was ca. 10% for 50cycles even at 50C, which means that the partial substitution of Mn in LiMn2O4 by Li substantially enhanced the capacity stability.