Abstract: The present invention relates to bleaching composition for keratin fibres, especially human hair, comprising at least one compound with bleaching and/or highlighting effect wherein a water soluble protein selected from water soluble silk protein, water soluble silk protein hydrolysate and their derivatives is added. The object of the present invention is aqueous composition for bleaching hair comprising three parts which are mixed prior to application onto hair and which are a—a substantially anhydrous composition comprising at least one compound with bleaching effect, b—an aqueous composition comprising at least one oxidizing agent, and c—a composition comprising at least one compound selected from water soluble silk protein, water soluble silk protein hydrolysate and of their derivatives.