TECHNOLOGY FOCUS - POLYMERS - Preferred Properties: The plastic material has hydrophobic behavior towards the percolating reactant, with mutual contact angle not less than 90 degrees.Preferred Materials: The fluorinated plastics are polytetrafluoroethylene, ethylene-chlorotrifluoroethylene, perfluoroalcoxy polymers, and tetrafluoroethylene-hexafluoropropylene. The plastic material is a coating applied to a metallic material.    TECHNOLOGY FOCUS - CHEMICAL ENGINEERING - Preferred Components: The porous planar component comprises a component(s) from foams, planar meshes consisting in crossing and overlapping of wires, planar meshes of interwoven wires, meshes with controlled profile, mattresses of wire coils, expanded meshes, or sintered layers. The current distributor consists in a first conductive foil with openings overlaid to a second conductive foil with openings of smaller dimensions than those of the first foil. The second foil is in contact with the gas diffusion electrode. The catalytic porous masses are inserted in the flow section of the gas. The elementary cells are in monopolar or bipolar electric connection. The cathodic compartment comprises an oxygen-fed gas diffusion cathode and a porous planar component fed with an alkaline hydroxide solution percolating in its interior. The anodic compartment comprises a hydrogen-fed gas diffusion anode and a porous planar compartment fed with a sulfuric acid solution percolating in its interior. The gas of the gas diffusion electrode is fed to the lower part and that the exhausted gas is discharged from the upper part of the cell.Preferred Materials: The first and second foils are from expanded meshes, meshes of wires, perforated sheets. The current distributor supports are elastic, and the current distributor exerts compression of the gas diffusion electrode and of the porous planar component against the ion-exchange membrane. The internal pressure of the compartment comprises the assembly made of current distributor, gas diffusion electrode and porous planar component. It is lower than the pressure of the other compartment, and that the membrane compresses the assembly.