With the use of isothermal saturation, solubility in the systems MgBr2-LiBr-H2O and Mg(NO3)(2)-LiNO3-H2O was determined at 0 and 50 degrees C. The pressure of water vapor in these systems was measured. Based on these data, the effect of hydration and association on the solution characteristics and the type of the crystallizing solid phase was elucidated.