To develop ionic polymer-metal composites (IPMC) with improved performance, three new ion-exchange membranes were prepared and employed in IPMC construction. The membranes were prepared by radiation-grafting of polystyrene sulfonic acid onto three fluoropolymers; poly(vinylidenefluoride-co-hexafluoropropylene),poly(ethylene-co-tetrafluoroethylene), and poly(tetrafluoroethylene-cohexafluoropropylene). The bending displacements of the IPMCs constructed with these membranes were at least several times larger than that of Nafion IPMC of similar thickness without straightening-back. The larger displacement was considered to be due to the higher concentration of ionic groups and consequent larger ion-exchange capacity.