The present invention relates to a composition for lightening keratin materials, preferably keratin fibres, in particular human keratin fibres such as the hair, comprising (a) hydrogen peroxide； (b) one or more carbonates and/or one or more carbonate-generating systems, (c) one or more polyphosphorus derivatives, in a total content of greater than or equal to 0.5% by weight, relative to the total weight of the composition, the pH of the composition being less than or equal to 9.7, the compositions being free of persalts. The invention also relates to a lightening process using said composition, and also to a multi-compartment device which is suitable for using said lightening composition.
