Computer aided design has become extremely popular and its use in classroom can be very helpful, adding more analysis capabilities to all chemical engineering areas. Process simulators, such as Hysys and Aspen, are complex tools and students tend to have doubts when they start using them. This article presents Hyduc, an exercise/tutorial software, developed to introduce process simulators to undergraduate students and to provide unit operation courses with realistic exercises involving simulation of chemical processes. (C) 2002 Wiley Periodicals, Inc.103155160