Abstract: A composite, porous, liquid-permeable article is provided which is a multilayer structure of discrete, bonded layers of porous, expanded polytetrafluoroethylene (EPTFE), which composite has its interior and exterior surfaces coated with a perfluoro ion exchange polymer to render the composite hydrophilic so as to resist gas locking in aqueous media wherein a composite diaphragm made therefrom, may also contain a water-soluble surfactant to assist in initial water penetration into the pores of the composite whereby an improved electrolytic cell is provided having the composite diaphragm as the porous separator in the electrolysis of alkali halide solutions and wherein the diaphragm is also useful as an improved filter medium.