FIELD: cosmetology. SUBSTANCE: the present method deals with dyeing keratin fibers and human keratin fibers, in particular, for example human hair by applying a dyeing composition (A) containing, at least, one precursor of oxidizing dyestuff and, possibly, one or several dye-forming substances, and N-acetylcysteine as a reducing agent. Color should be observed in air in alkaline, neutral or acid medium due to laccase being the constituent of composition (A) or composition (B), moreover, compositions (A) and (B) should be mixed directly before application or they should be applied one after another onto keratin fiber. The present method, also, deals with compositions for oxidizing dyeing, the method and the kit. Application of N-acetylcysteine as a reducing agent in case if laccase is applied as an oxidizing one does not inhibit escalation of oxidizing dyestuff by hair, compositions, according to the present innovation, provide shades of better chromaticity (more luminescent) and more intensive dyeing being highly resistant to perspiration, light and shampoo-type washing. EFFECT: higher efficiency. 24 cl, 4 ex, 2 tbl
