Polyaniline co-doped with Zn 2+ and H + was synthesized in aqueous HCl solution containing ZnCl 2 , and tested for its supercapacitive behavior in three-electrode or two-electrode system with 1.0M H 2 SO 4 as electrolyte by cyclic voltammetry, charge–discharge and electrochemical impedance spectroscopy (EIS). Scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) techniques were employed for characterization of polyaniline co-doped with Zn 2+ and H + . Compared with polyaniline doped with H + , it shows a larger specific capacitance of 369Fg −1 . Moreover, the specific capacitance remains 90% after 1000 cycles at a current density of 0.5Ag −1 , indicating good cycleability.