The molten salt method has in the past been employed to synthesize a large number of compounds at low temperatures. In this work we report the formation of solid solutions of BaTiO3–SrTiO3 and BaZrO3–SrZrO3 using a molten salt eutectic of NaOH–KOH as a solvent. Alkaline earth carbonates and titanium oxide were used as precursors for the titanate system, and alkaline earth carbonates and zirconium oxide were used as precursors for the zirconate system. It was found that both systems form solid solutions throughout the composition range. The implications of these results with regards to the applicability of the molten salt method as a tool to investigate low temperature phase equilibria are discussed.