The results of the study of ternary systems containing copper, cobalt, nickel, and cadmium halides and sulfates in binary water-organic and mixed organic solvents are summarized. The influence of the donor-acceptor properties of the ternary system components, the relative dielectric permittivity, and the intermolecular association in the mixed solvent on the solubility of salts and the crystalline structure of solvates is analyzed.