Disclosed herein are a method of dyeing or coloring, with a lightening effect, a human keratin material comprising applying a composition comprising, in a cosmetically acceptable medium, at least one fluorescent compound and at least one optical brightener; a composition comprising, in a cosmetically acceptable medium, at least one fluorescent compound and at least one optical brightener which are both soluble in the medium; and a device using such a composition comprising at least two compartments, wherein at least one comprises, in a cosmetically acceptable medium, a composition comprising at least one fluorescent compound and at least one optical brightener and optionally at least one additional ingredient chosen from direct dyes, oxidation bases and couplers, and at least one other compartment comprises a composition comprising at least one oxidizing agent.