Starting from isothermal excess volume data (two or more than two sets)

and based on the "pseudo-2-fluid theory"

a computation procedure of vapor-liquid equilibrium data is proposed: (1) Calculation of characteristic parameters of pure components:Vi

Pi and Ti; (2) Calculation of characteristic parameters of pseudocomponents:Vim

Pim and Tim;(3) Calculation of excess enthalpy H; (4) Calculation of Gibbs free energy G or its Q function; (5) Calculation of bubble point; ( 6 ) Calculation of vapor-liquid equilibrium data. The computation results for benzene-cyclohexane

benzene-n-hexane

ben-zene-n-heptane

benzene-n-octane

carbon tetra chloride-benzene

carbon te-trachloride-cyclohexane and carbon tetrachloride-n-heptane

compared with the corresponding vapor-liquid equilibrium experimental data and the data calculated directly from excess enthalpy

are satisfactory. Therefore

the proposed computation procedure is also appropriate to non-polar and slightly polar binary systems under relatively low pressures.