Liquid-liquid equilibrium (LLE) data for butyl tert-butyl ether + (methanol or ethanol) + water were measured experimentally at 298.15, 308.15 and 318.15 K. The experimental data were correlated with the NRTL and UNIQUAC equations. The equations were used to perform the correlation of each temperature data set and for the three temperatures data set simultaneously. The best results were found with UNIQUAC and NRTL (alpha = 0.1), respectively. Data prediction was carried out using the UNIFAC method, however the results found were not quantitative. (C) 2004 Elsevier B.V. All rights reserved.