We report here on the synthesis of layered nanosized LiNi0.5Mn0.5O2 compound by a modified self-combustion reaction and the studies of its electrochemical behavior as a cathode material for Li cells. Capacities up to 180-200 mAh/g could be reached during cycling of these electrodes even at 60 degrees C in LiPF6/alkyl-carbonate solutions. The nano-LiNi0.5Mn0.5O2 material exhibits remarkable stability during prolonged aging and cycling at elevated temperatures. Surface films developed on the nano-LiNi0.5Mn0.5O2 particles in the course of cycling/aging contain polycarbonates, LiF, nickel and manganese oxides, and fluorides, and lead to efficient passivation and stabilization of the electrodes. (c) 2006 The Electrochemical Society.