Phase equilibrium behavior of the system castor oil biodiesel + glycerol + methanol was studied to provide experimental data for the optimization of the separation downstream processes. Measurements of solubility were carried out for the ternary systems containing biodiesel derived from castor + glycerol + methanol at 298.15 K and + ethanol at (298.15 and 333.15) K. An increase of the system mutual solubility was observed with temperature. Binodal curves were determined by the cloud point using the titration method under isothermal conditions. The tie-lines for biodiesel + glycerol + methanol at 298.15 K were indirectly measured by analyzing the mixture density. The Othmer-Tobias correlation was used to ascertain the consistency of tie-line data. The results were correlated with the UNIQUAC model satisfactorily.