Chemical interaction in the Bi2Se3- Nd2Se3 system was studied by methods of physicochemical analysis (differential thermal analysis, X-ray phase analysis, microstructural analysis, microhardness measurement and density determination). Based on the analysis results, a phase diagram of the Bi2Se3- Nd2Se3 system was constructed. It has been established that the Bi2Se3- Nd2Se3 section is a quasi-binary section of the Nd-Bi-Te ternary system and belongs to the eutectic type. In the system, a solid solution area of 8 mol % Nd2Se3 is formed at room temperature based on Bi2Se3.The solid solution area was determined by microstructural analysis, to be 13 mol % at the eutectic temperature 813К and 8 mol % Nd2Se3 at room temperature. From the phase diagrams it is evident that in the Bi2Se3- Nd2Se3 section a new ternary incongruent-melting compound of the composition NdBiSe3 is formed by a peritectic reaction at a temperature of 995K with a component ratio of 1:1. According to the results of X-ray phase analysis, it was established that the NdBiSe3 compound crystallizes in the rhombic syngony with the lattice parameters: a =13,79; b=14,32; c=6,12 Å, Z=8, density pycnometric =6,42g/сm3, X-ray density g/cm3.