Displacement of the azeotropic composition of acetone/methanol system by using water as entrainer has been studied for different solvent:feed molar ratios (S/F = 1.0, 2.5, and 3.0) combined with pressure reduction, at 75.0 kPa. The vapor−liquid equilibrium data were compared to ASPEN Plus simulations using Wilson, NRTL, and UNIQUAC models. To determine the composition of the liquid and vapor phases, headspace-gas chromatography was used. For a solvent:feed molar ratio of 1.0 was obtained a complete azeotrope elimination. The obtained relative volatilities between 1.6 and 3.2 were for the assayed S/F ratios. Experimental data were well-represented by simulation with the UNIQUAC model, obtaining a vapor molar composition and temperature mean error of 0.009−0.027 and 0.80−1.70 K, respectively.