H + and Co 2+ ions co-doped polyaniline were synthesized by cyclic voltammetry onto the stainless steel mesh with various concentrations of cobalt chloride (CoCl 2 · 6H 2 O) in electrolyte. The structure and morphology of polyaniline (PANI) and PANI/Co 2+ films were characterized by Fourier transform infrared (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) techniques. The electrochemical properties of PANI and PANI/Co 2+ films were investigated by cyclic voltammetry, galvanostatic charge–discharge test, and electrochemical impedance spectroscopy (EIS) in 0.5 mol L −1 H 2 SO 4 electrolyte in a three-electrode system. The PANI/0.3 M Co 2+ film shows a larger specific capacitance of 736 F g −1 at a current density of 3 mA/cm 2 and lower resistance compared with the pure PANI film. The results indicated that the PANI/Co 2+ films are promising material for supercapacitors.