The thermal performance of the mechanical vapor compression (MVC) system was investigated. This work describes the mathematical and experimental study of the MVC system. The unit, with a capacity of 5 m(3)/d, is currently located in the heat transfer laboratory of the Atomic Energy Authority of Egypt. Some details of the operational features of the unit are presented, including a comparison of the data of the unit with both theoretical and experimental results. In the modeling, the overall mass and energy balance equations are given. The experimental and theoretical results indicated that the production rate increases by increasing the operating temperature from 70degreesC to about 98degreesC, "evaporator designed temperature70degreesC". Also, increasing the evaporator temperature has a good effect on the heat transfer coefficient.