Abstract: Co₃O₄ material was prepared by calcination in air atmosphere at 350℃ for 3 h of a precursor that obtained previously from room-temperature solid reaction using CoCl₂·6H₂O and NH₄HCO₃ as raw materials.X-ray diffraction（XRD）,transmission electron microscope（TEM） and infrared spectroscopy（IR） analysis results indicate that the obtained sample is nano-structured cubic spinel Co₃O₄.Cyclic voltammetry and AC impedance results show that the Co₃O₄ electrode exhibits reversible Faraday reaction characteristic and good kinetic property in 6mol·L^-1 potassium hydroxide aqueous solution.Galvanostatic charge/discharge results demonstrate that the alkaline Co₃O₄/AC hybrid capacitor using Co₃O₄ as positive electrode and activated carbon as negative electrode and 6mol·L^-1 KOH as electrolyte exhibit better charge/discharge performance and cyclic stability at high current densities.