The object of the present patent application is an agent for coloring keratin fibers based on oxidative dye precursors and containing (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 and a method for coloring keratin fibers by use of said agent.