Solubilities of bivalent metal oxides in molten alkaline chloride mixtures at 600 and 700-degrees-C have been studied by potentiometric titration techniques using an oxygen electrode Pt(02)ZrO2. For some oxides solubilities have been determined taking into account incomplete dissociation which has been confirmed by experimental data. Some correlations between physical characteristics of oxides (cations) and their solubilities in molten chlorides are discussed.