LiCoO2 powder used as cathode material for lithium ion battery was synthesized by microwave heating markedly affect the purity, morphology and electrochemical behaviors of the samples. X-ray diffraction (XRD) patterns display that the samples synthesized at 360 W for 10 min are pure layered LiCoO2, and SEM photos show that the powders are crystalline with well-defined facets whose sizes are about 5 μm. The performance of Co3O4 and starting materials by microwave heating and conventional heating was investigated. It is indicated that Co3O4 decomposes into CoO in microwave field at 750 ℃ and the mechanism of preparing LiCoO2 by microwave heating is different from that by conventional heating. The electrochemical behaviors of samples were tested. As a result, the highest specific discharge capacity is 134.3 mAh/g and the coulomb efficiency is 92.56%.