Thermophysical properties(solubility, vapor pressure, density, viscosity, heat capacity, and surface tension) of the H₂O/(LiBr+LiI+LiNO₃+LiCl) system (LiBr:LiI:LiNO₃:LiCl=5:1:1:2 by mole) were measured as a new working fluid for air-cooled absorption chiller. DÜhring(P-T-X) and enthalpy charts of the proposed system were constructed and the theoretical coefficient of performance of absorption chiller using the proposed system was calculated at various operating conditions. The transport properties of that system were measured and compared with those of the conventional H₂O/LiBr solution.