TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Catalyst: The catalyst is platinum or platinum alloy, and accelerates oxidation-reduction reaction in a fuel cell.Preferred Conductive Powder: The conductive powder particles are conductive carbon black or carbonaceous powder particles, chosen from furnace black, acetylene black, thermal black, channel black or ketjen black. The catalyst contains 0.1-30 mass% of fibrous carbon.Preferred Properties: At least a portion of the surface of the gas diffusion layer which is in contact with the catalyst layer, further contains spaces. In a cross-section of the gas diffusion layer, the cross-section area of spaces having a size of 0.1-50 microns accounts for at least 40% of the total cross-section area of all the spaces. The conductive substrate is porous.    TECHNOLOGY FOCUS - POLYMERS - Preferred Fibrous Carbon: The fibrous carbon is chosen from polyacrylonitrile-based carbon fiber, pitch-based carbon fiber or carbon nano-tube, preferably vapor grown carbon fiber which is heat-treated at 2300 degrees C, and contains 0.01-10 mass% of boron. The fibrous carbon has a fiber filament diameter of 10-300 nm and a fiber filament length of 100 microns or less.Preferred Resin: The water-repellent resin is a fluorine-based resin. EXAMPLE - Acetylene black bearing 50 mass% of platinum and graphitized VGCF product were mixed together to prepare a catalyst composition for a cell. The graphitized product was incorporated in an amount of 5 mass% into the primary components of the catalyst composition. To the prepared catalyst composition were added 5 mass% Nafion ion-exchange resin solution (in g) (1) and glycerine (5), and the resultant mixture was mixed to prepare a solution mixture. The solution mixture was applied on to a Teflon sheet and dried to form an electrode material containing a conductive substrate and a catalyst layer. Subsequently, a fuel cell was produced using the obtained electrode material. The electrode material peeled off from the sheet, was bonded to Nafion 112 ion-exchange membrane, to form a membrane-electrode assembly. The resultant membrane-electrode assembly serving as a gas diffusion electrode, was used as cathode hydrogen serving as a fuel gas and an oxidizing gas (air) were passed through the produced single cell, and the cell was operated at 0.1 MPa to evaluate the cell characteristics, which were found to be good.