In this article, we report polypyrrole (PPy)/poly(vinyl sulfonate) (PVS) and PPy/perchlorate (ClO4-) composite films generated by the electrochemical oxidation of pyrrole on a glassy carbon electrode (GCE) in an aqueous solution. The response of the produced films to an applied potential at 0.7 V was obtained by a cyclic voltammetry study in acetonitrile media. The films were significantly similar in their electrochemical behavior when ClO4- ions doped during the redox process. We concluded that with an increasing number of cycles, the anodic current increased because the number of the electroactive participants transported in the copolymer matrix was increased. Theoretical studies based on the Nernst and Butler-Volmer equations indicated that the ClO4- ion was transported during the oxidation/reduction process of the PPY/PVS and PPY/ClO4- films. The produced films were characterized further by means of IR spectroscopy, electrochemical impedance spectroscopy, and scanning electron microscopy to verify that the anion of ClO4- was doped into the copolymer matrix as well. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 117: 3107-3113, 2010