In chemical pulp bleaching, peroxide has found a strong position in alkaline stages. In the bleaching plant, hydrogen peroxide and distilled peracetic acid (dPAA) are excellent alternatives for delignification and bleaching, for example, when generation of chlorine dioxide causes a bottleneck in the process or because of environmental reasons. Hydrogen peroxide and dPAA can be used in the production of TCF and ECF pulps. In delignification and bleaching peracetic acid (PAA) can also be used simultaneously with chlorine dioxide as a combined stage.