(Liquid-liquid) equilibrium (LLE) data of the solubility curves and tie-line compositions have been determined for mixtures of (water + 2,3-butanediol + 1-butanol) at 298.15, 308.15 and 318.15 K and atmospheric pressure. Distribution coefficients and separation factors have been evaluated for the immiscibility region. The reliability of the experimental tie-lines has been confirmed by using Othmer-Tobias correlation. The LLE data of the ternary systems have been predicted by UNIFAC method. (c) 2007 Elsevier B.V. All rights reserved.