A kit of parts for reductively decoloring dyed keratin fibers comprising； a container (A) containing a cosmetic agent (a)；a container (B) containing a cosmetic agent (b)； and container (C) containing an aqueous, cosmetic agent (c) produced separately from each other, wherein； agent (a) in container (A) contains a reductant (a1) and agent (c) in container (C) contains (c1), wherein (c1) is one or more compounds of formula (I)； Wherein R1, R2, R3 independently represent H, CN, COOM, COOR4, CONR5R6, phenyl, a C1-10 alkyl group； M is selected from hydrogen, ammonium or a monovalent or multivalent alkali or alkali-earth metal cation； R4 is C1-16 alkyl； R5 and R6 are independently hydrogen or C1-6 alkyl； A is selected from COOM, COOR4 or (CH2)n-COOM； wherein n is 1-10. (a1) is preferably selected from sodium, zinc or potassium salts of dithionite； formamidine sulfinic acid and [bis(sulfinomethyl)amino]methane sulfinic acid or physiologically acceptable salts thereof. (c1) is preferably selected from maleic, fumaric, itaconic, palmitoleic or oleic acid. (C) preferably further comprises an additional organic or inorganic acid as specified herein. The invention further relates to a method for reductively decoloring dyed keratin fibers by using the multi-component packaging unit.
