The present invention relates to a process for dyeing and/or lightening keratin fibres, in particular human keratin fibres such as the hair, using b) one or more disulfide, thiol or protected-thiol fluorescent direct dyes and a) one or more direct dyes different from b).The present invention also relates to a cosmetic composition comprising the dyes defined above, and also to a multi-compartment device containing said dyes.The present invention also relates to the use of the dyes a) and b) for dyeing light or dark keratin fibres, without using an additional dye different from those defined above, for giving the fibres very chromatic, particularly visible colours.
