The purpose of the present work is to study the solid-liquid equilibrium in aqueous multi-electrolyte systems using the quasiisothermic thermometric technique (QTT). The principle of the QTT is based on thermal effects associated with the phase transformations that occur in the system. in order to test the apparatus, salt solubility data at 298.15 K for the aqueous systems H2O+NaCI+KCl, H2O+NaCl+Na2SO4, H2O+NiCl2+NiSO4 are presented. The data obtained for the three systems are in good agreement with the literature, including solid phase boundaries due to hydration. This agreement indicates the accuracy of the proposed method. Furthermore, the system with nickel salts are now experimentally determined.