Oxidative hair dyeing process with catalytic pretreatment

A pre-treatment solution for use in oxidatively dyeing hair comprises an aqueous solution of a complex of a transition metal ion, especially copper-II, and a chelating agent selected from 2,2 min -dipyridyl and o-phenanthroline. A pretreatment process with this solution serves to conform the oxidative dyeing rate of virgin hair to that of the normally noncongruent rate of nonvirgin hair, so as to enhance the efficiency of the oxidative dyeing process, without reducing the intensity or variety of color. A hair treatment package in kit form comprising the aqueous solution and an oxidative hair dye mixture is also disclosed.