Agents for the reductive decolorization of dyed keratin fibers contain, in a cosmetic carrier, (a) at least one compound of formula (I), A[(CR1R2)SO2M]p,q (I), in which A represents N(R3)3-q or O(R4)2-p, R1, R2, R4 represent a hydrogen atom or a C1-C6 alkyl group, R3 represents residues selected from the group of a hydrogen atom, a C1-C20 alkyl group, a C3-C8 cycloalkyl group optionally substituted with one to three C1-C4 alkyl residues, M represents residues selected from a hydrogen atom or an equivalent of an alkali metal ion, alkaline-earth metal ion, or metal ion, p represents 1 or 2, q represents 1, 2, or 3, wherein at least one of R1, R2, R4 represents a C1-C6 alkyl group if A represents O(R42-p), and R3 does not represent a hydrogen atom if q equals 1, and (b) optionally at least one compound of formula (II), A[(CR1R2)SO3M]p,q (II).
