Proton-conducting membrane for electrochemical use

A proton conducting membrane for electrochemical applications, especially for fuel cells, from a polymer based on a polymer with an aromatic ring but not a vinyl polymer, where the polymer with the aromatic ring has phosphonic acid groups, which are covalently bonded directly without spacer groups to the aromatic ring is new. Independent claims are included for: (1) the polymer with the aromatic ring, which is a prepolymer with phosphonic acid groups as above; and (2) a process for obtaining the base polymer (BP) by the steps: (a) bromination or iodination of the BP; (b) reaction of the halogenated BP in (a) with phosphonic and/or phosphoric acid esters in the presence of a transition metal catalyst, (c) hydrolysis of the polymer obtained in (b) and (d) conversion of the polymer obtained in (c) to a membrane in the form of a polymer film by a known method.