Abstract: An aqueous or aqueous-alcoholic composition for dyeing natural or synthetic fibers, especially hair, contains a combination of at least one cyclic oxo-substituted enediol according to formula I: ##STR1## wherein R.sub.1 and R.sub.2 are the same or different and independently of each other represent a hydrogen atom or an alkali metal atom, or R.sub.1 and R.sub.2 together represent an alkaline earth metal atom and n=0, 1, 2 or 3; and at least one member selected from the group consisting of malonic acid dinitrile, maleic acid diaminodinitrile, 2,5-diamino-6-nitropyridine, 1,2,3,4-tetrahydro-6-nitroquinoxaline, 7-amino-3,4-dihydro-6-nitro-2H-1,4-benzoxazine and substituted nitrobenzene compounds; as well as water and at least one cosmetic ingredient including solvents other than water, surfactants, thickeners, care materials and adjuvant materials.

Abstract: The dye-containing mass contains or consists of a compound of formula I: ##STR1## wherein R represents a DL-, D- or L-aldopyranose or a DL-, D- or L-ketopyranose, and X and Y, independently of each other, each represent a hydrogen atom, a halogen atom, a hydroxy group or an alkoxy group with from 1 to 4 carbon atoms; and, if needed, a direct-dyeing dye compound. The ready-to-use hair dye composition according to the invention is obtained by mixing this dye-containing mass with a hydrolase enzyme, e.g. a .beta.-galactosidase. The method for dyeing hair includes applying this ready-to-use hair dye composition to the hair.