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 T_m  510⁰C at room temperature reach 7 mol. % Gd₂Te₃.