TECHNOLOGY FOCUS - POLYMERS - Preferred Method: Step (C) involves using a substrate with a catalyst-containing coating; steps (D) and (E) may be carried out simultaneously to give a membrane which is self-supporting and coated with a catalyst layer. Step (E) may involve using a powder-coating process, or coating with a catalyst suspension (preferably containing non-polar organic solvent and/or phosphoric acid and/or PPA), or applying a catalyst-containing coating to a support and then transferring it (preferably by flow-moulding) to the membrane obtained in (C) and/or (D). Step (B) involves heating after forming a sheet of material as in (C). Step (D) involves treatment for 10 seconds to 300 hours at 0-150degreesC in presence of moisture. The membrane obtained after (D) and/or (E) is crosslinked by the action of oxygen. A layer with a thickness of 20-4000 microns is formed in step (C), a membrane with a thickness of 15-3000 microns is formed in (D), and the catalyst layer has a thickness of 0.1-50 microns.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Starting Materials: The mixture obtained in step (A) contains compounds which form polyazoles on heating, i.e. (hetero)aromatic tetra-amino compounds and di- or poly-carboxylic acids and/or diamino-carboxylic acids, preferably by heating in the melt at up to 400degreesC. Suitable compounds comprise:(a) 3,3',4,4'-tetra-amino-biphenyl, 2,3,5,6-tetra-amino-pyridine and 1,2,4,5-tetra-aminobenzene;(b) (hetero)aromatic di-acids or their derivatives, e.g. phthalic, isophthalic, terephthalic acids and various substituted derivatives thereof, diphenic acid, naphthalenedicarboxylic acids, benzophenone-4,4-dicarboxylic acid, biphenyl-4,4'-dicarboxylic acid, 4-carboxycinnamic acid etc. (35 di-acids listed);(c) tri- or tetra-acids and their derivatives, especially e.g. trimesic, trimellitic, benzene-1,2,4,5-tetracarboxylic, naphthalene-1,2,4,5-tetracarboxylic acid etc. (14 acids listed), in amounts of 0-30 (preferably 0.5-10) mol based on the amount of di-acid;(d) heteroaromatic acids, preferably pyridine-2,5-, -3,5-, -2,6- or -2,4-dicarboxylic acid, similar derivatives of pyrazole, pyrimidine, pyrazine or benzimidazole, pyridine-2,4,6-tricarboxylic acid, etc. (10 acids listed);(e) diaminobenzoic acids and/or their mono- or di-hydrochlorides.    TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Catalyst: The catalyst layer contains active particles with a size range of 0.1-10 microns, in amounts of 0.1-10 g/m2 of membrane surface. These particles contain platinum, palladium, gold, rhodium, iridium and/or ruthenium, and preferably also carbon.