An ionic liquid (IL) BMIZnCl3 has been synthesized by directly mixing zinc chloride (ZnCl2) and 1-butyl-3-methylimidazolium chloride (BMIC) with molar ratio l/l under a dry argon atmosphere. The density and surface tension of the IL in temperature range from 313.2 K to 343.2 K were determined. The value of thermal expansion coefficient and surface entropy were estimated by extrapolation. In terms of Glasser's theory, the standard molar entropy and lattice energy of the IL were estimated. Using the methods of Kabo and Rebelo, the molar enthalpy of vaporization of the IL, Delta H-g(l)m degrees at T = 298 K and Delta H-g(l)m degrees at the hypothetical normal boiling point were estimated. The thermal expansion coefficient, a, calculated by the interstice model is of the same order of magnitude as the experimental value. (C) 2007 Elsevier Ltd. All rights reserved.