Abstract: An electrochemical cell including an electrolyte retaining matrix layer located between and in contact with cooperating anode and cathode electrodes is disclosed herein. Each of the electrodes is comprised of a ribbed (or grooved) substrate including a gas porous body as its main component and a catalyst layer located between the substrate and one side of the electrolyte retaining matrix layer. Each substrate body includes a ribbed section for receiving reactant gas and lengthwise side portions on opposite sides of the ribbed section. Each of the side portions includes a channel extending along its entire length from one surface thereof (e.g. its outer surface) to but stopping short of an opposite surface (e.g. its inner surface) so as to provide a web directly between the channel and the opposite surface.