TECHNOLOGY FOCUS - POLYMERS - Preferred Components: An EM containing (i) e.g. an immobilized hydroxysilane as network builder as above, (ii) A Bronsted acid as under (1) above, (iii) zirconium and/or titanium phosphate as under (a3) above.A flexible EM for a fuel cell obtainable by (a) infiltration of a carrier and (a1) to (a3), as described above, and (b) stabilization of the carrier. as above.An EM including e.g. a Bronsted acid as above.An EM in which the hydroxysilylalkyl acid mentioned above has the formula (I): or (II)(((RO)y(R2)z)aSi(R1-SO3-)a)xMx+ (I)((RO)y(R2)zSi(R1-Ob-P(OcR3)O2-)a)xMx+ (II)R1 = linear or branched 1-12C alkyl or aryl, 5-8C cycloalkyl or a unit of formula (III) or (IV)n, m = 0-6M = H or NH4x = 1-4y = 1-3z = 0-2y+z = 4-a ist (sic)b, c = 0 or 1R, R2 = Me, Et, propyl, butyl, or HR3 = Me, Et, propyl, or butylAn EM in which the hydroxysilylalkyl acid of e.g. sulphur or phosphorus, as above.The hydroxysilylalkyl acid of sulphur or phosphorus is immobilized with a hydrolyzed compound of phosphorus or a hydrolyzed nitrate, oxynitrate, oxychloride, carbonate, alcoholate, acetate, acetylacetonate, of a metal or semimetal, or a hydrolyzed compound obtained from diethyl phosphite, diethylethyl phosphonate, titanium propylate, titanium ethylate, tetraethylortho silicate, tetramethylorthosilicate, zirconium nitrate-, oxynitrate-, propylate-, acetate-, or acetylacetonate, phosphoric acid methyl ester, or precipitated silicic acid.The proton conducting ceramic particles are selected from the oxides: Al2O3, SiO2, ZrO2, or TiO2, and these particles have one or more particle size fractions of mean particle diameter 10-100 and/or 100-1000 nm.The composite is a ceramic coating of oxides, carbides, or nitrides of titanium, silicon, zirconium or aluminum.The composite is based on a substrate containing polymer fibers, and of thickness 10-150, preferably 10-50 micron. At room temperature the conductivity of the EM is at least 5 mS/cm, preferably 50 mS/cm.The EM has an external proton conductive layer on one or both side which is insoluble in methanol. Infiltration of the material permeable carrier is continuous.The proton conductive anode and cathode layers have the same composition, the catalyst support in both layers is electrically conductive, and consists of carbon black, graphite, charcoal, activated carbon or metal oxide, and the anode and cathode layers can have different catalysts.The catalyst is platinum, palladium or ruthenium.The pore builder is ammonium carbonate bicarbonate.The mobile system can be an automobile and the stationary system a household energy system.Preferred Process: The EM is heated to a temperature of at least 80, preferably at least 120degreesC. EXAMPLE - A quantity of AlCoA CT 1200 SG(RTM)(aluminum oxide)(150 g) was suspended in a sol previously stirred for 2 hours containing (g): ethanol (160), 5 wt.% aqueous hydrochloric acid solution (15), tetraethoxysilane (10), methyltriethoxysilane (2.5), and Dynasilan GLYMO(RTM)(7.5), the mixture obtained was homogenized, and was applied to a PO nonwoven of thickness 30 micron continuously with a roller to give finally a microfiltration membrane of mean particle size 450 nm.