A systematic computer aided analysis of the process model is proposed as a pre-solution step for integration of design and control problems. The process model equations are classified in terms of balance equations, constitutive equations and conditional equations. Analysis of the phenomena models representing the constitutive equations identify the relationships between the important process and design variables, which help to understand, define and address some of the issues related to integration of design and control. Furthermore, the analysis is able to identify a set of process (control) variables and design (manipulative) variables that may be employed with different objectives in design and control for the integrated problem. The computer aided model analysis is highlighted through illustrative examples, involving processes with mass and/or energy recycle, where the important design and control (structure selection) issues for the integrated problems are considered. (C) 2002 Elsevier Science Ltd. All rights reserved.