The construction of a phases tree of a ternary system with three binary compounds KCaCl3 , K2 BaCl4 , CaBaCl4 is given. The phase tree includes four secondary phase triangles CaCl2 –KCaCl3 –СаBaCl4 , CaBaCl4 –KCaCl3 –BaCl2 , KCaCl3 –BaCl2 –K2 BaCl4 and KCaCl3 –CaBaCl4 –KCl. These triangles are connected by three stable secants KCaCl3 –СаBaCl4 , KCaCl3 –BaCl2 , KCaCl3 –K2 BaCl4 . Crystallizing phases in stable and secant elements correspond to the simplex tops.
