The chlorination behavior of LiCoO2 (LCO) was investigated as a function of the reaction temperature (400-600 ℃) and time (1-8 h) under a 190mL/min Ar+10mL/min Cl2 flow. Based on the results of a structural analysis, a sequential reaction mechanism was proposed for the chlorination of LCO: LiCoO2(400-600 ℃) Li1-xCoO2- y→(450-600 ℃) Co3O4→(500-600 ℃) CoCl2. It was also found that thermal decomposition of the Li1-xCoO2-y phase to the LiCoO2 and Co3O4 phases occurs simultaneously in the temperature range of 550-600 ℃, resulting in reduced Li removal ratios. A change in the reaction temperature caused significant changes in the reaction product in terms of the constituent phases and their ratios because each reaction step is independently affected by the reaction temperature. In consideration of the highest Li removal ratio (0.86 after 8 h of the chlorination) and potential loss of Co by sublimation of CoCl2 at elevated temperatures, the optimum suggested temperature for the chlorination of LCO is 500 ℃.