Mixing is an example of a process where the selection of the equipment is practically realized "by hand". There are the following benefits from the introduction of knowledge-based system in mixing equipment selection : faster evaluation and generation of alternatives, systematic search of alternatives, and storage of experience. The subject of this paper is an expert system for the selection of mixing type. The main factors that are taken into account in the selection process are phases to be mixed, mixing requirements, residence time, mixing applications, maintenance, cost, type of application, and viscosity. The discussed mixing types are mixing in stirred vessel, dynamic in-line mixer, static in-line mixer, jet mixing in tanks, tee-pipe or injector, pneumatic mixing, roll mill, colloid mill, and kneader. In the presented system the knowledge base is separated in an MS-EXCEL spreadsheet, Nexpert Object acts as an inference machine, and MS-EXCEL spreadsheets work as a user interface. Two examples of mixing type selection are presented.