Dynamic characteristics of a multi-stage solar distillator were studied by formulating the rate equations and the heat and mass balance equations with respect to the process variables. The results obtained by the simulation showed satisfactory agreement with the data taken from both a laboratory test plant having 5 stages with 1 m2 and a field test plant having 10 stages with 3 m2 in frame area. The operation conditions required to maximize the distillate productivity were predicted on four sample days through a year. Then sensitivities of the distillate productivity were estimated. Availability of using concrete slab instead of the solar energy recieving plate was also substantiated. © 1987.