The agent for coloring keratin fibers is based on oxidative dye precursors and contains: (a) at least one hydrazone derivative of formula (I) or a physiologically compatible salt thereof, (b) at least one coupler or a physiologically compatible salt thereof, and (c) a persulfate salt as oxidant. A multicomponent kit for coloring keratin fibers and a method of coloring keratin fibers using the agent are also provided ##STR00001##