Liquid-liquid equilibrium (LLE) data for the ternary systems of (water-formic acid-1-undecanol), (water-acetic acid-1-undecanol). (water-propionic acid-1-undecanol), (water-butyric acid-1-undecanol), and (water-valeric acid-1-undecanol) were investigated at 298.15K and atmospheric pressure. Complete phase diagrams were obtained by determining solubility and tie-line data. The tie-line data were compared with the results predicted by the UNIFAC, modified UNIFAC (Dortmund), and modified UNIFAC (Lyngby) methods and correlated by means of UNIQUAC model. The reliability of the experimental tie-line data was confirmed by using the Othmer-Tobias correlation. Distribution coefficients and separation factor values were evaluated for the immiscibility region. (C) 2012 Elsevier By. All rights reserved.