In this paper, for the first time, an experimental study is conducted of phase equilibria in two three-component NaCl–NaBr–Na2CO3 and NaCl‑NaBr‑Na2SO4 salt systems. The compositions and temperatures of points of interest for the creation of functional materials are established. Projections of phase complexes onto composition triangles include two fields of crystallization: sodium carbonate (sodium sulfate) and a solid solution of NaClxBr1–x. Phase equilibria are described for crystallization fields and monovariant curves.