There have been many efforts to apply Artificial intelligence (AI) principles to the complicated problem-domains of engineering. In particular, although Al involves several areas, such as knowledge-based expert system, natural language processing, robotics, vision, etc. knowledge-based expert systems seem to have been of most interest to the engineering domain. A prototype expert system, BIO-EXPERT, was developed to act as an intelligent assistent to aid a biochemical process engineer in determining key parameters and optimal process conditions for the partition of proteins between two aqueous polymer phases. All knowledge in this system was organized into a unique hierarchical knowledge-base, and represented using an IF-THEN rule-based formalism. The system uses a forward-chaining inference mechanism and a pattern-matching process with a conflict-resolution strategy. The prototype system was implemented in common LISP on a SUN 3/50 workstation.