LiNi0.5Co0.2Mn0.3O2 cathode material was coated with MoO3 via a wet coating process. X-ray diffraction patterns show that the coating surface is composed of MoO3 and Li2MoO4. The 3 wt.% MoO3 coated LiNi0.5Co0.2Mn0.3O2 cathode (Li2MoO4 is treated as equivalent mole of MoO3) exhibits the best improved cycling performance. It performs a capacity retention of 90.9% after 100 cycles while that of the pristine material is only 82.8%. After being coated by 3 wt.% MoO3, the rate performance is also greatly enhanced and the charge transfer resistance is greatly decreased. The improvement of electrochemical performance is related to the fact that the coating layer diminishes the side reactions between the cathode and the electrolyte.