Isobaric vapor-liquid and vapor-liquid-liquid equilibria were measured for the water-ethanol-hexane system at normal atmospheric pressure. The apparatus used for the determination of vapor-liquid-liquid equilibrium data was an all-glass dynamic recirculating still with an ultrasonic homogenizer coupled to the boiling flask. The experimental data demonstrated the existence of a ternary heterogeneous azeotrope at 329.2 K with a composition of 0.105, 0.236 and 0.658 mol fraction of water, ethanol and hexane, respectively. The experimental vapor-liquid and vapor-liquid-liquid equilibria data were found to be thermodynamically consistent. The correlation of these data was carried out using NRTL and UNIQUAC models and predicted with UNIFAC. The equilibrium data of the system were compared with other hydrocarbon systems previously analyzed and commonly used as entrainers in the dehydration of the ethanol by azeotropic distillation such as benzene and cyclohexane. (c) 2007 Elsevier B.V. All rights reserved.