A mixed hardwood Kraft pulp was used after oxygen delignification to produce pure cellulose for dissolving purposes. A totally chlorine-free bleaching and purification process was designed. It comprises an acid hydrolysis step in the presence of a metal chelating agent (EDTA) followed by a peroxide delignification stage under oxygen pressure catalyzed by a Cu(II)phenanthroline complex, a cold caustic extraction and finally, an ozone stage carried out under neutral conditions. High purity cellulose with less than 5% xylans could be produced. Both the catalyst and the ozone stage have an effect on the DP of the cellulose which then can be varied depending on the requirements.