Abstract: A fully supported membrane assembly for an electrochemical fuel cell is provided. A first and second layer of porous electrically conductive sheet material, such as carbon filter paper, has a solid polymer ion exchange membrane interposed therebetween. The layers of sheet material cover and support the membrane over substantially its entire surface area. The layers of sheet material are coated with a catalyst to tender them electrochemically active. The layers of sheet material and the membrane are bonded together to form a consolidated assembly. Openings are formed in the layers of sheet material and the membrane to accommodate the passage of fluids through the assembly. Seals are formed by impregnating the layers of sheet material with a sealant material which generally circumscribes the fluid passage openings and the electrochemically active portion of the assembly.