The substances that make up the three-component reciprocal system of fl uorides and chlorides of potassium and cadmium have various applications, both individually and in mixtures. The faceting elements of the ternary reciprocal system include in binary systems the formation of compounds KF∙CdF2 , KCl∙CdCl2 of congruent and compound 4KCl∙CdCl2 of incongruent melting. The crystallization tree is constructed. Taking into account the compounds, a crystallization tree has been constructed that has a linear structure and includes fi ve stable secondary triangles. The triangles are separated from each other by four stable secants, of which three secants have a quasi-binary character. The crystallization tree allows one to predict crystallizing phases in secondary phase triangles. In four secondary phase triangles, the formation of triple points of invariant four-phase equilibria is noted. The secondary phase triangle KCl–K4 CdCl6 –KCdF3 does not contain an invariant point. The system of fl uorides and chlorides of potassium and cadmium belongs to the adiagonal triangulate type. Chemical interaction under standard conditions is described. Modeling of chemical interaction for fi gurative points of composition corresponding to intersections of stable and unstable secants has been carried out using thermodynamic data of the starting materials and binary compounds. The formation of three equivalence points is noted on two stable secants. On the other two stable secants, two equivalence points are noted. According to thermodynamic calculations, for two mixtures out of ten, reactions cannot be realized under standard conditions. The proposed technique for describing chemical interactions can be used for other types of ternary reciprocal systems with exchange reactions with both diagonal and diagonal types of partitioning. Mixtures corresponding to equivalence points on unstable secants with a heat eff ect of reactions greater than 50 kJ can be used as single-action exothermic mixtures.