TCF bleaching of sulfite pulp is relatively easy. With only two stages it delivers brightness levels up to 88% ISO on low Kappa number pulps. Very high brightness, however, is difficult to reach. High Kappa pulps or pulps which are delignified with magnesium oxide in order to allow an effluent recycle are even more difficult to bleach because of their lignin residual. This limits the potential to bleach mag-nefite pulps to very high brightness or to use higher Kappa pulping in the acid sulfite process for improved strength properties. A treatment with acidic peroxide is capable to improve the delignification if activated with molybdate. The abbreviation used in this paper for such a stage is P_a~*, peroxide, acidic and activated. The lower lignin residual allows higher brightness in a subsequent alkaline peroxide stage. With a three stage approach, an oxygen supported first extraction, an acidic P stage and a final P treatment, namely sequences like Eop-P_a~*-P or OP_((MgO))-P_a~*-P, even pulps with very high initial Kappa can be bleached to >89 %ISO.
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