ChemSep 5.0 is the latest version of a software system for modeling distillation, absorption, and extraction operations. ChemSep integrates flash, the classic equilibrium stage column model and a nonequilibrium or rate-based column model in one easy-to-use program. ChemSep 5.0 includes a GUI for Windows that allows export of results in a variety of formats including spreadsheet, word processor, and html. ChemSep is distributed by the CACHE Corporation, a nonprofit organization for Computing Aids for Chemical Engineering Education.