an electrolyte / electrode assembly for a solid electrolyte fuel cell includes a pair of flat electrodes spaced from one another and a solid electrolyte element sandwiched between the electrodes . a porous matrix having one side and comprising at least one chemical constituent which provides the porous matrix with a coefficient of thermal expansion corresponding to the coefficient of thermal expansion of the solid electrolyte element , has one of the flat electrodes formed on or within the one side of the porous matrix . an electrically conductive material is supported in the porous matrix for providing an electrical conductivity in the porous matrix in the direction of thickness of the flat electrodes .