Deacidification of vegetable oils can be performed by liquid-liquid extraction. The present paper reports experimental data for the system corn oil + oleic acid + ethanol + water at 298.15 K and different water contents. The addition of water to the solvent reduces the loss of neutral oil in the alcoholic phase and improves the solvent selectivity. The experimental data were correlated by the NRTL and UNIQUAC models, with a global deviation of 0.89% and 0.92%, respectively.