A method for making a composite membrane includes the steps of coating a first layer of ionomer on an intermediate support, laminating a dry porous support into the wet first layer of ionomer, impregnating the porous support with ionomer from the coated ionomer layer, optionally drying the impregnated porous support and the first layer of ionomer, coating a second layer of ionomer on the impregnated porous support, drying the second layer of ionomer until most of the solvent is evaporated, and delaminating the composite membrane from the intermediate support. The composite membrane thus obtained includes a porous support impregnated with the ionomer and on each side of the impregnated support a dense ionomer layer.