1. A diagram of stable existence of chloride phases in equilibrium with a metallic solution has been constructed for the four-component Fe-Cr-Cl-H system. 2. It is shown that in the chlorination of iron and chromium an equilibrium is set up in which either gaseous chlorides alone or both liquid and gaseous chlorides can coexist with a metallic Fe-Cr solution. 3. Gaseous phase compositions have been determined ensuring the optimum values of parameters and the required degree of impregnation of iron with chromium from a chloride phase, as well as conditions necessary for the continuous impregnation of iron with chromium. It is shown that, to achieve this, provision must be made for the escape of gases from the container. 4. Using calculated data, it is possible to determine the optimum conditions for the diffusion impregnation of iron alloys with chromium through a chloride phase.