On the basis of the analysis of structure and concentration dependences of physical properties in a number of ternary solid solutions based on IV‐VI semiconducting compounds, certain specific features of solid solutions between chemical compounds caused by the chemical interaction in solid solutions are revealed. They include the formation of microheterogeneous structure of the solid solution, the existence of a threshold of complex formation, a non‐quasibinary character of the sections passing through two congruent compounds in the range of small impurity concentrations, the appearance of extrema in the dependences of properties on composition along the isoconcentrates in the Gibbs triangle in the points corresponding to intersections with a quasibinary section, etc. The situation is complicated when the host compound contains a high concentration of native defects. The revealed peculiarities have universal character, i.e. the same phenomena must be typical for multinary solid solutions of different types.