Solubility of salts in the systems MCl2-H2O-Solv (M = Co, Ni) and CoBr2-H2O-Solv (Solv = dimethyl sulfoxide, dimethyl formamide, and dimethyl acetamide) at 25A degrees C was measured experimentally. Dominating species of cobalt and nickel halides existing in various concentration regions were identified by analysis of electron absorption spectra. It was shown that the major factor defining solubility is the interaction of halocomplexes of metal ions with solvent molecules.