The invention relates to a process for the gel or surface postcrosslinking of water-absorbing polymers in which the polymers are treated with a surface postcrosslinking solution and during or after the treatment are postcrosslinked and dried by means of an increase in temperature, the crosslinker being a compound of the formula in which R1 and R2 independently of one another are H, hydroxyl, phenyl or C1-C6-alkyl, R3 is hydrogen, C1-C12-alkyl, C1-C12-alkenyl or C6-C12-aryl and R4 and R5 independently of one another are C1-C12-alkyl, C1-C12-alkenyl, C6-C12-aryl, hydroxyl, C1-C12-alkoxy or hydrogen, dissolved in an inert solvent, to water-absorbing polymers which can be obtained by said process, and to their use in hygiene articles, packaging materials and nonwovens.