Tricyclic 5-6-5 heteroaromatic keratin dyeing compounds having two heteroatoms. Compositions for the oxidative dyeing of keratin fibers, comprising a medium suitable for dyeing and one or more tricyclic 5-6-5 heteroaromatic keratin dyeing compounds having two heteroatoms. A method for oxidative dyeing of keratin fibers, comprising applying such compositions in the presence of an oxidizing agent, for a period sufficient to develop the desired coloration.