The copolymer of pyrrole and aniline, poly(pyrrole-co-aniline), has been prepared by chemical oxidation of corresponding monomer mixtures with ammonium peroxysulfate. Techniques of FTIR, SEM-EDS, and BET surface area measurement were used to characterize the structure and morphology of the copolymer. The electrochemical properties of the copolymer were investigated by cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy. The results indicated that poly(pyrrole-co-aniline) was about 100-300 nm in diameter and showed better electrochemical capacitive performance than polypyrrole and polyaniline. The specific capacitance of the copolymer electrode was 827 F/g at a current of 8 mA/cm(2) in 1 mol/L Na2SO4 electrolyte. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 115: 1881-1885, 2010