The invention relates to a process for the preparation of crosslinked polymers bearing nitroxide groups, which are prepared by a method frequently called atom transfer radical addition polymerization (ATRA). A further aspect of the invention is the use of such polymeric crosslinked nitroxides as stabilizers for polymers against the detrimental influences of heat and UV light, as stabilizers against premature polymerization of vinyl aromatic monomers and as active electrode materials in secondary batteries.