Spinel LiMn2O4 powder, used as a cathode material for lithium-ion batteries, is prepared from a water-in-oil emulsion by loading the lithium and manganese ions into the aqueous phase. For optimum electrochemical properties, both the heating temperature and the time are controlled. As the heating temperature is increased, the particles grew linearly and the specific surface-area is reduced. The LiMn2O4 phase starts to form at 450 degrees C and is produced up to 750 degrees C for 48 h without the development of other phases. Optimum heating conditions, based on the resulting electrochemical properties, were 750 degrees C and 850 degrees C for 48 h. The capacities of the powders are 112 and 115 mA h g(-1), respectively.