Liquid-liquid equilibrium (LLE) data are important for designing and modeling of process equipment. In this article, the group method of data handling (GMDH) technique has been used to estimate LLE data of the quaternary system of corn oil + oleic acid + ethanol + water at 298.15 K. Using this method, a new model has been proposed that is suitable for use in predicting LLE data. The equilibrium data presented herein were predicted using the GMDH model. To evaluate the performance of the GMDH method, we compared the data predicted using the proposed model with experimental data. Moreover, we compared the deviation between the experimental data and the data estimated with the GMDH. We also used the deviations of some existing models for the comparison. The results show that the proposed model can be used as an efficient tool for estimating LLE data.