The characteristics of CoO prepared from the calcination of Co(OH)2 (precursor of CoO) in the N2 atmosphere were analyzed, and the charge/discharge properties of CoO was also investigated in this paper. Increasing the calcination temperature from 200 to 900°C the grain size of CoO increased from 6.59 to 31.5nm, and the BET surface area decreased from 89.83 to 0.47m2 g−1. For CoO calcinated at 200°C the maximum charge capacity, the coulomb efficiency and the irreversible capacity at the first cycle of Li/CoO battery were found to be 1233.57mAhg−1, 98.46% and 305.87mAhg−1, respectively. The irreversible capacity in the first cycle could be recovered in the following charge/discharge cycles.