(Liquid + liquid) equilibrium (LLE) data for the ternary system (water + butyric acid + cyclohexyl acetate) have been determined experimentally at T = (298.15, 308.15 and 318.15) K. Complete phase diagrams were obtained by determining solubility and the tie-line data. Tie-line compositions were correlated by the Othmer-Tobias method. The UNIFAC method was used to predict the phase equilibrium in the system using the interaction parameters determined from experimental data between CH, CH2, CH3, COOH, CH3COO and H2O groups. It is found that UNIFAC group interaction parameters used for LLE could not provide a good prediction. Distribution coefficients and separation factors were evaluated for the immiscibility region. (C) 2004 Elsevier Ltd. All rights reserved.