The invention relates to an ion-conductive polymer membrane for a fuel cell, whereby the polymer membrane is configured from a polymer-forming hydrocarbon material and to a method for producing the same. The membrane also has a metal-containing gel which has been hydrolysed and/or condensed from a metal alkoxide starting material and which is deposited in the polymer and/or is chemically bonded to the polymer. The proportion of metal alkoxide by weight, in relation to the membrane, lies between 25% and 1%.