In order to provide a theoretical basis and fundamental data for industrial utilization of insoluble potassium rocks to produce potassium salts, the phase equilibrium of the ternary system K2CO3-Na2CO3-H2O at 323.15 K, 343.15 K and 363.15 K was determined using the isothermal dissolution equilibrium method. According to the experimental results of salt solubility, the phase diagrams were constructed and the crystallization zones are discussed in detail. All of the solubility isotherms at 323.15 K, 343.15 K and 363.15 K consist of two invariant points, three univariant curves and three crystallization fields corresponding to Na2CO3 center dot H2O, K2CO3 center dot Na2CO3 and K2CO3 center dot 1.5H(2)O, respectively. The densities of the liquid phase of the ternary systems were investigated as well. (C) 2017 Elsevier Ltd.