The conditions for the Pa and Ch steps have been 1 developed using mathematical experiment planning. Two experiments were planned according to the Box plan (at m = 3) and the effect of bleaching chemicals (HO and 22 sodium chlorite), temperature and duration of processes
on hardwood pulp were studied. The hardwood pulp yield as well as the degree of penetration at the initial steps and the pulp whiteness in the second experiment has been chosen as the indicators entirely characterizing the delignification and bleaching processes.