A new method for the calculation of vapor-liquid equilibrium (VLE) of nonaqueous volatile strong electrolyte solutions has been developed. This method is demonstrated by comparing calculated data with experimental results of HC1-CH3OH system. The activity coefficients of HC1 and CH3OH at 298.15K can be satisfactorily correlated up to 8 molality by estimating the ionic association constant Kx = 1.7×l02 and the short-range-force parameter W=-2.15 with the association model of Pitzer and Li (1984). After deriving the temperature dependence of both the model parameters and the Henrys constant of HC1 in methanol

it is possible to predict the VLE for HC1-CH3OH system at 101.3kPa and about 340K. The mean deviation of boiling points and vapor phase mole fractions between measurements of this study and calculated results are 0.73K and 0.0014 respectively.