The system of solid solutions (Sn0.8Ge0.2)1−yTey with the values of y = 0.499; 0.505; 0.510 is investigated by means of the Mössbauer effect on the 119Sn nucleus within the temperature range 160 to 300 K. The effective Debye temperature and mean‐square displacements of tin atoms from equilibrium are calculated. In the region of phase transition (about 200 K) fractures on the temperature dependencies of the isomer shift and Debye temperature are observed, while no anomalies of the Mössbauer effect probability are noticed. No quadrupole interaction is observed with the symmetry decrease in the lattice. A correlation between the isomer shift and interatomic distance is revealed. The ionicity of the chemical bond in the system SnxGe1−xTe is ≈︁ 54%, when x = 0.9, and about 40%, when x = 0.1.