Liquid-liquid equilibria for the ternary system castor oil + soybean oil + hexane are studied at 298.15 K. Mixtures are equilibrated in a temperature-controlled water bath. After evaporation of hexane, the oil compositions of each phase are determined by a combination of gravimetric measurements and the analysis of fatty acid methyl esters (FAMEs) using gas chromatography. Since castor and soybean triglycerides, are a mixture of five or six fatty acids, the castor and soybean fractions are characterized by the relative concentration of ricinoleic acid. Fitting the K-ratios for castor off, soybean oil, and hexane smoothed the liquid-liquid equilibrium data. A computational cross-flow extraction is designed on the basis of the smoothed phase diagram and is experimentally validated.