6 ] 2 ) were determined. In addition, the solubilities of six ILs in six lower alcohols, water, acetonitrile and diethyl ether were measured at 288.15 K; and the hydroscopicity of above five ILs were measured at the temperature of 298.15 K and relative humidity of 79% for 24 h. Densities of five ionic liquids were determined between 283.15 and 333.15 K. Then the densities of five binary system (ILs/acetonitrile) were explored between 283.15 and 333.15 K, the type of the ionic liquid, the concentration of five ILs in CH 3 CN, and the effect of temperature on the binary systems, were correlated with the measured data.