The solubilities and the physicochemical properties including density, viscosity, refractive index, conductivity, and pH of the aqueous ternary system (LiCl + Li2SO4 + H2O) at T=308.15 K and p = 0.1 MPa were determined using the isothermal evaporation method, and the metastable phase diagram and the physicochemical property diagram versus composition of liquid phase solution for the system at 308.15 K were plotted. In the metastable phase diagram of the ternary system at 308.15 K, there is one invariant point, two univariant curves, and three crystallization zones corresponding to lithium sulfate monohydrate (Li2SO4 center dot H2O), lithium chloride monohydrate (LiCl center dot H2O) and (Li2SO4 center dot H2O + LiCl center dot H2O). It belongs to the hydrate type I, and neither double salts nor solid solution were found. On the basis of Pitzer ion-interaction theory of the electrolytes and the chemical equilibrium HMW model, Pitzer single-salt parameter of lithium chloride at 308.15 K was fitted, and the single-salt parameters of lithium sulfate, mixing ion-pair theta(Cl,SO4), and the Debye-Huckel limiting slope A(Phi) at 308.15 K were obtained according to the temperature-dependent equation of parameters presented in the literatures. And then, the solubilities on the ternary system (LiCl + Li2SO4+ H2O) at 308.15 K were calculated. A comparison shows that the calculated solubility agrees well with the experimental data. (C) 2015 Elsevier B.V. All rights reserved.