A computer package has been developed for design and simulation of thermal desalination processes. This was motivated by the unavailability of such packages in the literature or on a commercial scale. The package includes models for various systems of single effect evaporation (SEE), multistage flash (MSF), and multi effect evaporation (MEE). The MSF systems include brine circulation, brine mixing, once through, and thermal vapor compression. The MEE configurations include parallel and forward feed systems. The SEE and MEE systems include stand-alone and vapor compression units. Vapor compression systems include mechanical, thermal absorption, and adsorption heat pumps. All models are based on a well developed set of materials and energy balance equations as well as correlations for evaluation of physical properties, heat transfer coefficient, and thermodynamic losses. All mathematical models have been developed and previously tested and validated by the authors against available industrial and literature data. All models generate the design and simulation variables which have the strongest effect on the unit product cost. These include the thermal performance ratio, the specific heat transfer area, the conversion ratio, the specific power consumption, and the specific flow rate of cooling water. The computer package includes displays for process design, rating, flow charting, performance calculations, help files, and graphing of process schematics and performance curves. The package allows for parameter selection, printing of forms and data files, and selection of parameters for performance charts. The package performs checks on parameter range and prevents pinch conditions in various heat exchange processes. The package has been tested in a number of undergraduate, graduate, and training classes and is found simple to use and provides fast and accurate results.