Polyaniline-poly(styrene sulfonate) (PAn-PSS) composite films have been synthesized by electropolymerization of aniline in aqueous media containing Poly(styrene sulfonic acid). The electrochemical behavior of the film was studied in aqueous and organic electrolyte solutions using cyclic voltammetry and constant-current polarization techniques. In acidic aqueous solutions, the PAn-PSS composite film showed a reversible redox reaction accompanied b cation transfer. The redox activity in organic electrolyte solutions depended on the composition of the solution measured. The composite film showed low redox activity during the initial cycles in 1 mol dm-3 (M) LiClO4 solution of propylene carbonate (PC). The redox activity of the film increases significantly on repeated scans in a mixed solvent system (PC + 1,2-dimethoxyethane (DME)). Electron probe microanalysis experiments proved that the redox reaction of the composite film in organic electrolytes was accompanied by a cation (Li+) transfer process between the film and the organic electrolyte. The coulombic efficiency of charge-discharge cycling under constant-current polarization was nearly 100% after the redox activity reached a steady state.