Polypyrrole(PPy)/LiMn2O4 composites were prepared by chemical oxidation of pyrrole onto LiMn2O4 with dodecylbenzene sulfonate as a dopant. The polymerization occurred mainly on the surface of LiMn2O4 to yield the entirely coated LiMn2O4 particles. The capacity of the cell reached the maximum of 124 mAh/g at 4.1 wt% of PPy in the active material. The composite cell showed enhanced charge-discharge properties compared with a pure LiMn2O4 cell. The PPy may enhance the electron exchange ability and stabilize the structure of LiMn2O4.