In a fuel cell assembly typically comprising a plurality of cells each comprising an electrolyte layer (2), a pair of gas diffusion electrode layers (3, 4), and a pair of flow distribution plates (5), each flow distribution plate is provided with a central recess (51, 52) having a number of projections (53, 54) formed therein; and an electrode terminal layer (55, 56) is formed on each projection to establish a connection with an external circuit; each gas diffusion electrode layer defining the passages for fuel and oxidizer gases by covering the central recess, and provided with a porous layer (3a, 4a) typically in the form of a nano-tube carbon film, formed over each flow distribution plate. Because the porous layer is directly formed on each flow distribution plate, the thickness of each gas diffusion electrode layer can be freely controlled, and the overall thickness of the assembly can be minimized so as to allow a compact design.