The present invention relates to a membrane electrode assembly wherein each gas diffusion substrate comprises a porous electrically conductive gasket member is located on the first and second planar faces of a peripheral portion of the sheet material. The electrocatalyst layers are not present adjacent to the gasket members and the edge of the membrane is sandwiched between the gasket members. The invention further relates to integrated cell assemblies and fuel cell stacks comprising membrane electrode assemblies according to the invention.