TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Reinforcement: The reinforcement consists of oxidic material, preferably containing zirconium (Zr), silicon (Si) and/or titanium (Ti). It preferably is in the form of inorganic fibers or filaments, non-woven and/or woven fabric.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Reagents: The reinforcement is modified with a coupling reagent, preferably silane, preferably applied by condensation on the reinforcement, preferably a basic silane of formula (1), especially a basic silane coupling reagent of formula (2).(RO)nSiBm (1)(MeO)mSi((CH2)lNH2)v (2)n, m, v = 1, 2, 3;l = 0-12;n+m, v+m = 4;R = alkyl or aryl, preferably Me;Me = methyl;B = a basic group, especially a nitrogen compound selected from primary, secondary or tertiary amines and amides, heterocyclic N compounds, especially 5- or 6-membered heterocycles, e.g. pyrazole, imidazole, triazole, oxazole, thiazole, pyridine, pyrimidine or condensed N-ring systems.Trimethoxysilylamine, (MeO)3SiNH2, is especially suitable.    TECHNOLOGY FOCUS - POLYMERS - Preferred Membranes: The membrane is a polymer electrolyte, especially cation exchange, membrane. Preferred polymers with acid properties are polymers, copolymers and/or blends, preferably selected from polymethyl methacrylate, perfluorinated polystyrene, PTFE, copolymers of sulfonated styrene-divinylbenzene, sulfonated polyether-sulfones, polysulfones, polyether-ether-ketones, polyimides, polybenzimidazoles, polyacetylenes, polypyrroles, polythiophenes, polyanilines and/or polyphenylenes. EXAMPLE - A thin glass fiber non-woven was etched in a 1 M aqueous sodium hydroxide solution (10 seconds at 50 degrees C), washed well with deionized water and dried (10 minutes at 30 degrees C). It was then dipped in 50% 3-aminopropyltrimethoxysilane solution in ethanol (10 seconds at room temperature), shaken to remove excess solution and dried (30 minutes at room temperature + 10 minutes at 100 degrees C). The modified non-woven was placed slowly on a film of 15% solution of Nafion (RTM; equivalent weight 1100), of uniform thickness, on a glass plate, then the solution was dried (15 minutes at 140 degrees C). The surface was then given a 200 mum thick coating of a Nafion (RTM) solution and dried (15 minutes at 140 degrees C). Finally, the membrane was separated from the glass in a water bath, dried with fluff-free paper, fixed to another glass plate with adhesive tape on the edges and dried (2 minutes at 120 degrees C). The mechanical integrity of the composite was determined by repeated cycles of swelling and drying, in which is was wetted in water at 80 degrees C for 20 cycles and dried for 10 minutes at 95 degrees C. Optical examination of the fracture properties of the membrane indicated that it did not split.