This work presents a solubility isothermal titration calorimetry (solITC), a new calorimetric method that allows the determination of solubility product (K-sp) and heat of solution (Delta H-sol degrees) of hydrophobic ionic compound in water. Based on a single titration of dilute ionic solution into its counterionic solution the method consists of observing the abrupt change of the heat flow signal due to hydrophobic phase separation and fitting the integrated heats to exact thermodynamic model. A priori analysis shows that the applicability range spans for K-sp determination over five orders of magnitudes (typically 10(-9) < K-sp < 10(-4) for vertical bar Delta H-sol degrees vertical bar approximate to 30 kJ center dot mol(-1)) keeping at least 5% precision in both K-sp and Delta H-sol degrees values. For K-sp < 10(-10), only Delta H-sol degrees can be precisely determined. The method performance was validated on forming three different types of precipitate with different levels of solubility and heat of solution at T = 298.15 K. The new method is applied to explore 18 cation-anion combinations for possible ionic liquid formation. (C) 2014 Elsevier Ltd. All rights reserved.