İn recent years, the range of information about the chemistry of transition elements has expanded significantly. Thus, new types of complex compounds were synthesized, their structures were studied and unusual physico-chemical properties were revealed. Most of these compounds have found applications in various fields of industry and agriculture. Among the transition elements located in D. İ Mendeleev's periodic table, the scope of the chemistry of complex compounds of rhenium, located in the additional subgroup of the seventh group, is wider and more colorful. Because, unlike other transition elements, it can show the degree of oxidation from -1 to +7 in its compounds. In addition, rhenium is known for its unusual physical and chemical properties, high melting temperature (318 °C), resistance to corrosion in various environments, etc. due to its properties, it is superior to other metals and is currently used in a number of important fields of modern technology. İn the conducted research, a new complex combination of tetravalent rhenium with orthonitroaniline [NO2-C6H4NH3]2ReCI6 was synthesized, and their thermal transformations in the solid phase were studied by many thermogravimetric and İR spectroscopic methods. It was determined that Anderson grouping occurs first during heating, and then Re+4 is reduced to metallic rhenium as a result of the oxidation-reduction process. İt is known from the literature that a number of compounds of rhenium, including complexes with organic donor bases, can be used as a starting material in obtaining oxide or metallic coatings, as well as as a catalyst in many organic synthesis processes. [1] Despite the fact that there are enough materials in the literature about the synthesis and research of complex compounds of tetravalent rhenium with various amines [2-6] and phosphines [7, 8], there is very little information about its compounds with aromatic amines during the search. In the presented article, the interaction of potassium hexahalogenorenate K2ReX6 (X=CI-) with orthonitroaniline (NH2-C6H4-NO2) was studied and the physicochemical properties of the obtained complexes were studied.