The vapour pressures of liquid (3-diethylaminopropylamine (3-DEPA) + cyclohexane) were measured by a static method between T = (273.15 and 363.15) K at 10 K intervals. The excess molar volumes V-E at 298.15 K and excess molar enthalpies H-E at 303.15 K were also measured. The molar excess Gibbs free energies G(E) were obtained with Barker's method and fitted to the Redlich-Kister equation. The Wilson equation was also used. Deviations between experimental and predicted G(E) and H-E, by using DISQUAC model, were evaluated (c) 2010 Elsevier Ltd. All rights reserved.