By the complex methods of physico-chemical analysis: differential-thermal, X-ray diffraction, microstructural, as well by microhardness and density measurements the character of interaction in the system (Bi2Te3)1-x(Gd2Te3)x has been studied and mikrodiagrams have been plotted. It is established that at introducing Gd2Te3 into the compounds Bi2Te3 solid solution form and their some physico-chemical properties change. Its is determined that Bi2Te3 based solid solution with composition in 16 mol. % Gd2Te3 and Tm 5100C at room temperature reach 7 mol. % Gd2Te3.