The linear actuation of polypyrrole (PPy) films polymerized at 0.85 V (versus Ag-wire) and -27 degrees C in propylene carbonate solutions of tetrabutylammonium trifluoromethanesulfonate (TBACF(3)SO(3)) was investigated in the same monomer-free electrolyte. The actuation properties were evaluated by electrochemomechanical deformation measurements (ECMD) during cyclic voltammetry and potential step experiments. The ECMD response revealed mixed-ion actuation behaviour for the film, namely the polymer film actuation was dominated by cation movement at potentials less than 0V and anion movement at potentials greater than 0V, with film lengthening seen at both potential extremes. It was found that the ratio of cathodic to anodic actuation can be modulated by the scan rate. Longer-term actuation (50 potential steps from -1V to 0 V, or from 0V to + 1V), indicated better film stability when cycled in the anodic region. Changing the electropolymerisation potential to a higher value of 1.2 V led to a modification in ECMD characteristics for the PPy/CF3SO3 films. (c) 2006 Elsevier Ltd. All rights reserved.