Artificial muscles have been fabricated in the form bilayer strips using an insulating polymer layer and polypyrrole (PPy) conducting polymer film, and the force produced by them during redox processes have been investigated. This study reports the effects of anions in the polymerization electrolyte and the cations in the cycling electrolyte on the force generated by such muscles. The size of anions used during polymerization of PPy films have greater effect on the force produced by the muscles made with such films. Higher forces are obtained with larger surfactant anions. Size of cations in the cycling electrolytes also plays a major role in determining the force exerted by the muscles. (C) 2004 Elsevier B.V. All rights reserved.