Process for stabilizing solutions of peroxidic compounds used for bleaching

Process for bleaching paper pulp or cellulosic fibers by contacting the paper pulp or cellulosic fibers with a stabilized solution containing water, a peroxidic compound used for bleaching and a stabilizer, which stabilizer is at least one polymer derived from an alpha-hydroxyacrylic acid, which polymer is a homopolymer and contains units of the formula:

• ##STR4## where R.sub.1 and R.sub.2 represent hydrogen or an alkyl group comprising from 1 to 3 carbon atoms which can be substituted by a hydroxyl group or a halogen atom, R.sub.1 and R.sub.2 being identical or different, and where M represents a sodium or potassium atom or an ammonium group, said peroxide compound being present in an amount between 0.01 and 30% by weight relative to the weight of solvent, said polymer having an average molecular weight of between 2,000 and 800,000 and being present in an amount between 0.01 and 30% by weight relative to the weight of water.