An ionic liquid (IL) BMIZn3Cl7 has been synthesized by directly mixing zinc chloride and 1-butyl-3-methylimidazolium chloride (BMIC) with molar ratio 3/1 under dry argon atmosphere according to the procedure of Lecocq and Abbott. The density and surface tension of the ionic liquid were measured in the temperature range from 318.2 to 343.2 +/-0.1 K. The estimation of physico-chemical properties of BMIZn3Cl7 was carried out. The thermal expansion coefficient and surface entropy were derived from the experimental data. In terms of Glasser's theory, the standard molar entropy and lattice energy of the ionic liquid were estimated. Using the methods of Kabo and Rebelo the molar enthalpy of vaporization of the ionic liquid, Delta H-g(l)m(degrees) at 298 K and Delta H-g(l)m(degrees) at the hypothetical normal boiling point were estimated. According to the interstice model, the calculated thermal expansion coefficient is in the same order of magnitude as the experimental value. (C) 2008 Elsevier B.V. All rights reserved.