The present invention relates to a multi-compartment device or kit for dyeing keratinous fibers, in particular human keratinous fibers, such as the hair, comprising a first compartment including a dyeing composition (A) comprising one or more oxidation dyes and one or more alkaline agents and a second compartment including a composition (B) comprising one or more oxidizing agents the said device also comprising one or more self-foaming agents having a boiling point of at least 1° C. present in at least one of the compositions (A) and/or (B). The invention also relates to a ready-for-use self-foaming dyeing composition and to a method for dyeing keratinous fibers employing this composition.
