Dehydration of i-PrOH by heteroazeotropic distn. with isooctane, i-Pr2O and cyclohexane was modeled by using the non-random 2 ligs. equation for phase equils. calcn. The coeffs. of this equation for the considered ternary mixts. were fitted to the vapor-lig.-lig. equil. data and simultaneously to the vapor-lig. equil. data. Phase mail. in the resp. ternary systems were computed and the accuracy of the description of the lig.-lig. equil. for the systems formed in the decanter was presented.