TECHNOLOGY FOCUS - CHEMICAL ENGINEERING - Preferred Cell: In cell (B), the contact area is not less than 70%. The catalyst layer of the GDE is applied to the IEM. Preferred Membrane: The IEM has a (I) layer with an embedded support. Alternatively, it has not less than 2 (I) layers with a support between them or embedded in one layer, in which case the layers preferably have different equivalent weights. (I) preferably has an equivalent weight of 600-2500, especially 900-2000, with the layer of higher equivalent weight on the GDE side. The support of the IEM consists of a mesh, woven, braided, knitted or nonwoven fabric or foam of plastically or electrically deformable material, preferably metal, plastics, carbon and/or glass fibers. EXAMPLE - Gas diffusion electrodes (GDE) were tested with a laboratory cell having an electrochemically active area of 100 cm2. The electrodes had a proton-conducting ion exchange membrane (IEM) of the perfluorosulfonic acid type with an equivalent weight of 950. The membrane was supported by an embedded woven glass fiber fabric. The GDE had an electroconductive substrate of carbon fabric with a gas diffusion layer of acetylene black-PTFE mixture. This was provided with a catalyst layer of rhodium sulfide sorbed on carbon black, mixed with PTFE. As this electrode was operated in direct contact with an IEM, it was also coated with Nafion (RTM; proton-conducting ionomer) to improve bonding. This oxygen-consuming cathode had an almost smooth surface, apart from shrinkage cracks typical of the production process. It was provided with a contact of expanded titanium with a titanium/ruthenium (Ti/Ru) mixed oxide coating. A commercially-available anode of expanded titanium-palladium metal with a Ti/Ru mixed oxide coating was used. Operating at 5 kA/m2, 60degreesC with 14% technical hydrochloric acid and a spacing of 3 mm between the anode and the IEM pressed hydrostatically onto the cathode with 200 mbar, the operating voltage of the test cell was 1.16 V when operated continuously for 16 days.