An oxidizing composition for keratin fibres, comprising, in a cosmetically acceptable medium:
- (a) at least one oxidizing agent which is hydrogen peroxide or a compound capable of producing hydrogen peroxide by hydrolysis, or a mixture thereof,
- (b) at least one copolymer based on acrylamido-2-methylpropanesulphonic acid and acrylamide, and
- (c) at least one polymer which is a crosslinked 2-acrylamido-2-methylpropanesulphonic acid homopolymer or amphiphilic copolymer comprising at least one sequence of 2-acrylamido-2-methylpropanesulphonic acid units and at least one unit comprising a hydrophobic portion.