Abstract: The invention relates to a catalyst component for isocyanate modification, comprising at least one cyclic ammonium salt having a cation of the formula I wherein Y is a linear or branched C2-C20 segment which is substituted by a hydroxyl group in the 2 position to the charge-bearing nitrogen atom and optionally bears further substituents and is optionally interrupted by heteroatoms from the group of oxygen, sulfur, nitrogen and aromatic rings and optionally has further rings, and the N-bonded substituents R1 and R2 are either independently identical or different, substituted or unsubstituted, optionally branched, aliphatic C1-C20 radicals, aromatic C6-C20 radical or araliphatic C7-C20 radicals or the N-bonded substituents R1 and R2 form a ring segment X with one another for which the same or different definition given above for Y is applicable, with the proviso that X has a hydroxyl group as substituent in the 2 position to the charge-bearing nitrogen atom or does not have a hydroxyl group as substituent in th