The On-Line MORPHYLANE(R) Advanced Control System MACS has been developed by Krupp Koppers as a sophisticated tool for plant operation optimization. Rigorous plant simulation models reflect the process and create the basis for the calculation of the main plant parameters as well as the related controller setpoints. The system and its interaction with a DCS have been successfully tested at the Krupp Koppers offices. The improvement of plant economics under MACS supervision is mainly due to improved benzene recovery from the feedstock without any deterioration of the product quality specified.