This work deals with the application of a multicriteria optimization technique for the optimization of a jack pine pulping process, which has a large number of input-and output variables. The optimization process is mainly comprised of two steps: reduction of the volume of the search spate and determination of good compromise solutions. In the first step, the Pareto domain is approximated by a large number of possible solutions. The optimization technique uses them concept of preference, indifference and veto to determine the best solutions. Results show that an optimal solution zone can be defined and zones of decreasing preference can be drawn.