One subject of the invention is a composition comprising: (a) at least one cationic surfactant of formula (I) or (I´) below: where: R1, represent a hydrogen, a C1-C6 alkyl, optionally bearing at least one hydroxyl or alkoxy R2, which may be identical or different, represent a C1-C6 alkyl R3 representing a C8-C32 hydrocarbon-based radical, optionally bearing at least one hydroxyl -CH20-R3 with R3 representing a C8-C32 hydrocarbon-based radical, optionally bearing at least one hydroxyl n is equal to 2 or 3 p is equal to 0 or 1 and the sum of n and p is equal to 3 R1, represents a C1-C6 alkyl, optionally bearing at least one hydroxyl or alkoxy R2 represents a C1-C6 alkyl, optionally bearing at least one hydroxyl or alkoxy a radical -CH2-CH(OH)-[CH(OH)]n-H with n representing an integer ranging from 1 to 4 R3 representing a C8-C32 hydrocarbon-based radical, optionally bearing at least one hydroxyl a radical -CH(OH)-(CH20)P-R"3 with R"3 representing C8-C32 hydrocarbon- based radical, optionally bearing at least one hydroxyl, p being equal to 0 or 1 m is an integer ranging from 1 to 3 X" represents a counterion and (b) at least one oxidizing agent (c) at least one dye or at least one alkaline agent, or mixtures thereof. Other subjects of the invention include a method for treating keratin fibres, in which this composition is applied, and also a multicompartment device comprising, in a first compartment, a composition that is free of oxidizing agent and, in another compartment, a composition comprising this oxidizing agent, the cationic surfactant(s) of formula (I) or (I´) being, without preference, in one and/or the other of the compartments. The invention finally relates to the use of these cationic surfactants of formula (I) or (I´) for dyeing or bleaching human keratin fibres, especially the hair.La présente invention concerne une composition comprenant : (a) au moins un tensioactif cationique de formule (I) ou (I´) ci-dessous : où : R1 représente un hydrogène, un alky
