Liquid-liquid equilibrium data are presented for mixtures of tetrahydrothiophene 1,1-dioxide (sulfolane) + 1-heptyne (or +benzene or +p-xylene) + heptane and for mixtures of sulfolane + benzene + decane (or +dodecane) at 303.15 K. The addition of benzene to sulfolane is found to increase the solubility of hydrocarbons (heptane > decane > dodecane). The influence of benzene on the solubility of the hydrocarbons is greater than that of p-xylene or of 1-heptyne. The relative mutual solubility of benzene is higher in heptane + sulfolane mixtures then in decane + sulfolane or dodecane + sulfolane mixtures. Three three-parameter equations have been fitted to the results. These equations are compared and discussed in terms of statistical consistency. The NRTL and UNIQUAC models were used to correlate the experimental results and to calculate the phase compositions of the ternary systems. The UNIQUAC equation fitted the experimental data better than the NRTL equation : the average mean square deviations phase composition error was 0.011 for UNIQUAC as compared to 0.027 for NRTL.