Abstract: A membrane assembly which comprises a layer of perfluorinated polymer which has carboxylate functional groups, a layer of perfluorinated polymer which has ion exchange functional groups, and a water-containing or water-soluble stratum which lies between these two layers and joins them together, is described. Such a multilayered composite membrane is more simply made than conventional multilayered membranes having adherent layers, and provides for easy recovery of the component parts thereof. The membrane assembly is useful for separating the compartments of an electrochemical cell, especially a chloralkali cell.