New interpenetrating elastomeric networks have been prepared in which the high tension in the first network is balanced by the compression of the second network. The composite films exhibit high electrically induced strain without need for any external mechanical prestraining. Strains of up to 233% in terms of area expansion have been obtained at an electrical field of 300 MV m(-1). These new electro-elastomers may have applications as actuators (see figure) and artificial Muscles.