The vaporliquid equilibrium (VLE) data for the binary system isopropyl alcohol + dimethyl sulfoxide (DMSO), isopropyl acetate + DMSO, and ternary system isopropyl alcohol + isopropyl acetate + DMSO were measured with a VLE modified Othmer still at 101.3 kPa. The experimental data were proved to be thermodynamically consistent when the point-to-point consistency test of Van Ness test was applied. The binary experimental data were correlated with the nonrandom two-liquid (NRTL), Wilson, and universal quasichemical (UNIQUAC) activity coefficient models. Then, the ternary VLE data were predicted with the obtained binary interaction parameters. The results indicate that the values of equilibrium temperature and vapor mole fraction calculated by the NRTL, Wilson, and UNIQUAC models are in good agreement with the experimental data. When the mole ratio of the binary azeotrope to DMSO was 1:1.5, the binary azeotrope of isopropyl alcohol and isopropyl acetate was eliminated. Therefore, DMSO is a potential extractive agent to separate the azeotrope by extractive distillation.