The InSb₂Se₃S–InSe system has been studied using differential thermal analysis, X-ray diffraction, micro structural analysis , and density measurements , and its phase diagram has been constructed . It has been established that the join is a quasibinary section of the quaternary system In,Sb||S,Se. Compounds InSb₂Se₃S and  InSe forms eutectic  containing 30 mol. % InSe, = 450⁰C. At room temperature, solubility based on InSb₂Se₃S reaches up to 10 mol.% InSe, and InSe on the – basis of  3 mol. % InSb₂Se₃S