Liquid-liquid equilibrium (LLE) data for (water + ethanol + trans-decalin) were measured at atmospheric pressure and in the temperature range of 300.2-315.2 K. A type I liquid-liquid phase diagram was obtained for this ternary system, as (trans-decalin + water) is the only liquid pair that is partially miscible. The experimental data for this system were predicted with the UNIFAC model. The reliability of the experimental tie-line data is determined through the Othmer-Tobias plots. The root mean square deviation between the observed and calculated mole percents was 8.14%. (c) 2006 Elsevier B.V. All rights reserved.