TECHNOLOGY FOCUS - POLYMERS - Preferred Process: Electropolymerization is carried out in 2-1000 successive cycles. The supporting electrolyte-containing organic solvent has a viscosity of more than 2 mPa.s, and preferably consists of a mixture of isopropanol and sulfuric acid or a mixtuure of dichloromethane and imidazolium or pyridinium type ionic liquid(s). Alternatively at least one of the supports carries two membranes of sintered material placed on each side of the MGFE (inserted between the MGFE and the opening in the support), in which case the supporting electrolyte-containing solvent preferably consists or a mixture of acetonitrile or dichloromethane with salt(s) (specifically tetrabutylammonium tetrafluoroborate). The monomer (I) is selected from pyrroles, thiophenes, polyfluorenes and anilines, all optionally functionalized by primary amino, carboxy, aldehyde, hydroxy and/or halo functional group(s). The process optionally also includes a preliminary stage for fixing catalyst(s) (II) active in the electrochemical reduction of molecular oxygen (specifically selected from cobalt tetraaza-anulenes and iron or cobalt porphyrins or phthalocyanines) to a reactive group of the polymer; or a subsequent step for fixing (II) (in this case specifically a metal catalyst containing one or more of platinum, palladium, ruthenium, tungsten, niobium, tantalum, manganese, iron, osmium, vanadium, chromium, titanium, molybdenum, aluminum, iridium, lead and their alloys) to the polymer-coated MGFE product. EXAMPLE - A starting metallized graphite felt element (MGFE) consisted of a disk formed from a mat of graphite fibers (BET surface 0.7 m2/g; diameter 20-25 mu m) homogeneously coated with a 1 mu m layer of nickel. The MGFE was inserted between two supports (each having an opening providing liquid access to the MGFE and one having an electrical connection), with a porous membrane between the MGFE and each support, to give a working electrode. The electrode was incorporated in an electropolymerization cell. 200 ml of acetonitrile containing pyrrole at 0.05 M and tetrabutylammonium tetrafluoroborate at 0.1 M was added to the cell, and electropolymerization of the pyrrole onto the MGFE was carried out in successive cycles, each consisting of a phase of applying a current of 150 mA for 30 seconds and a rest phase of 1 minutes, for 15 minutes. A homogeneous coating film of polypyrrole was obtained throughout the MGFE.