This work introduces a benchmark problem of a pulping process, including both the fiber line and the chemical recovery area. The complete details of the pulp mill process are presented, including the control objectives, modes of operation, process constraints, measurements and costs. The dynamic model, including the source/binary code of all the unit operations is made available to the academic community as a benchmark for use in process system engineering studies. (C) 2003 Elsevier Ltd. All rights reserved.