In order to reduce the cost of cathode materials, microwave synthesis method has been applied in the fast preparation of spinel LiMn2O4 by using LiOH . H2O and MnO2 (CMD) as starting materials. The structure, microstructure and electrochemical performance of the final product have been investigated. For optimum synthesis, the spinel LiMn2O4 should be prepared at a temperature between 700 degrees C and 750 degrees C. LiMn2O4 synthesized in optimum conditions delivers an initial charge capacity of 133 mA h/g, and exhibits good rechargeability.