In this work, experimental liquid-liquid equilibrium data for the ternary system water + acrylic acid + 4-methyl-2-pentanone were determined at 298.15 K and atmospheric pressure. The experimental data were also compared with the values correlated by the NRTL and UNIQUAC models. Good quantitative agreement was obtained with these models. In general, the average deviations from the NRTL model are slightly greater than those from the UNIQUAC model. The reliability of the experimental tie-line data was confirmed by using the Othmer-Tobias correlation. Distribution coefficients and selectivity were evaluated for the immiscibility region.