A predictive model for vapor-liquid equilibria of ternary systems, composed of two solvents and one electrolyte, is developed. The parameters for ternary systems are calculated from those for the constituent pairs of binary systems with simple mixing rules. Two isothermal and three isobaric sets of experimental data obtained from the literature and from our laboratory are compared with those calculated by this proposed model. The results are quite satisfactory, with average absolute error of vapor phase mole fractions of less than 0.0193.