LiMn2O4 exhibits lower cost, acceptable environmental characteristics, and better safety properties than other positive-electrode (cathode) materials for lithium-ion batteries. In this study, excess Li doped Li1+x Mn2O4 is synthesized by a well-mixed co-precipitation method with LiOH utilized as both the reactant and co-precipitation agent. The precursor is calcined for various heating times and temperatures to form a fine powder of a single spinel phase with different particle sizes, size distributions, and morphology. The minimum heating temperature is around 400°C. For short heating periods, Mn2O3 impurity is observed, but disappears after longer heating times. The average particle size is in the range 2–8μm for powders calcined between 700 and 870°C. The lattice parameter increases with increase in heating temperature. The electrochemical behavior of LiMn2O4 powder is examined by using test cells which consist of a cathode, a metallic lithium anode, and an electrolyte of 1M LiPF6 in a 1:1 (volume ratio) mixture of ethylene carbonate (EC) and dimethyl carbonate (DMC). Cells with cathodes of LiMn2O4, Li1.08Mn2O4 and Li1.1Mn2O4 give a capacity of 85, 109 and 126mAhg−1, respectively. The introduction of excess Li in LiMn2O4 apparently increases the capacity, and decreases significantly the rate of capacity degradation on charge–discharge cycling.