The vapor pressure of heptene-(S) was determined. Vapor-liquid equilibria of two binary systems
i.e. toluene-heptene-(3)
n-heptane-heptene-(3)
and the ternary system toluene-n-heptane-heptene-(3) were determined with the Gillespies type equilibrium still. With the equilibrium data of the following three binary systems i.e. n-heptane-toluene
?heptane-heptene-(3)
toluene-hcptene-(3) the vapor-liquid equilibrium of the ternary system toluene-n-heptane-heptene-(3) was calculated by means of Spinners and Whites equation respectively. The calculated results were found to be coincident with the experimental data.