Condition diagram of the Sb2Te3–La2Te3 cut has been researched by the differential, thermal, X-ray, microstructural analysis methods as well as microhardness and density measurement. It was found that cut is the quasibinary section of La– Sb–Te triple system. In the system there forms triple chemical combination consists on LaBiTe3 crystallized in hexagonal lattice with the following parameters: a=4.24 c=30.64 Å (c/a=7.21). Solubility on Sb2Te3 side at room temperature is 6 mol.%. Electrophysical properties of LaSbTe3 compound have been investigated too.