Electrochemomechanical deformation (ECMD) studies have been performed in the electrochemically prepared freestanding film of ferricyanide ion doped polypyrrole (PPy). The ECMD studies conducted on these polymer films show an increasing order of deformation in accordance with the extent of solvation of the alkali metal cation (K+ < Na+ < Li+) of supporting electrolyte in aqueous medium. The excess charge on Fe(CN)(6)(3-/4-) in addition to negative charge generated over the PPy film during the electrochemical reduction was compensated by inserting supporting electrolyte cation, at an extended potential range of -0.85 to + 0.7 V vs. Ag/AgCl. The appearance of an appreciable magnitude of deformation in the PPy film in a smaller potential window of -0.25 to + 0.6 V indicates a significant contribution of Fe(CN)(6)(3-/4-) dopant towards the total deformation of the polymer film. (C) 2004 Elsevier B.V. All rights reserved.