Isobaric vapor-liquid equilibrium data (VLE) at 101.325 kPa have been determined in the miscible region for 1, 1-dimethylethoxy-butane (BTBE) +methanol+ water and 1,1-dimethylethoxy-butane (BTBE) +ethanol+ water ternary systems, and for their constituent binary systems, methanol+BTBE and ethanol+BTBE. Both binary systems show an azeotrope at the minimum boiling point. In the ternary system BTBE + methanol + water no azeotrope has been found, however, the system BTBE + ethanol + water might form a ternary azeotrope near the top of the binodal. Thermodynamically consistent VLE data have been satisfactorily correlated using the UNIQUAC, NRTL and Wilson equations for the activity coefficient of the liquid phase. Temperature and vapor phase compositions have been compared with those calculated by the group-contribution methods of prediction ASOG, and the original and modified UNIFAC. Predicted values are not in good agreement with experimental values. (c) 2007 Elsevier B.V. All rights reserved.