Polyaniline (PANI) films were electrochemically synthesized on graphite electrode and their ion-exchange selectivities for ClO4- were investigated. Cyclic voltammetry (CV) results showed that PANI-H2SO4 film represented higher selectivity for ClO4- than PANI-HCl and PANI-HClO4. Furthermore, the CV records of PANI-H2SO4 film in different acidic solutions demonstrated that ClO4- exchange was performed in a lower potential range (from -0.025 V to 0.097V), which is distinguished from SO42- and Cl-. Additionally, chronoamperomertry (CA) studies of PANI-H2SO4 film in 0.1 M various acidic solutions (H2SO4, HCl and HClO4) confirmed that the diffusion coefficient values in HClO4 (13.319/18.184 x 10(-6) cm(2) s(-1)) were the biggest during doping/de-doping process. The exceptional ion-exchange selectivity for ClO4- was explained by the process of dominant accumulation, quick insertion of anions, and the sluggish mobility of ClO4- inside the membrane. Results of present work demonstrated that PANI may serve as a promising membrane for ClO4- removal by ion-exchange process. (C) 2011 Elsevier Ltd. All rights reserved.