Co3O4 microspheres were synthesized by a simple hydrothermal treatment. The first-cycle charge-discharge tests were carried out between 0.6 and 0.6 V vs. SCE. The pristine, discharged and recharged specimens were characterized by X-ray power diffraction and scanning electron microscopy. Cyclic voltammetry (CV) curves of Co3O4 at various concentrations in LiOH solution were investigated. The appearance of the two pairs of redox peaks indicated that two sets of faradaic reactions were involved in the redox reactions of Co3O4 to LiCoO2 and LiHCoO2.