Isothermal vapor-liquid equilibrium (VLE) for diethyl sulfide + n-hexane at (338.15 and 323.15) K and diethyl sulfide + 1-hexene at (333.15 and 323.15) K were measured with a circulation still. All systems exhibit a slight positive deviation from ideality. No azeotropic behavior was found in any of the systems studied. The experimental results were correlated with the Wilson model and also compared with the original UNIFAC and the COSMO-RS predictive models. The measured diethyl sulfide + n-hexane VLE have been used simultaneously with the excess enthalpy from literature for a correlation of temperature-dependent Wilson parameters. Excess molar enthalpies at 318.15 K for the diethyl sulfide + 1-hexene system were calculated from the VLE data. Analyses of liquid- and vapor-phase compositions were determined with gas chromatography. All VLE measurements passed the thermodynamic consistency tests that were used (integral, infinite dilution, and point test).