The investigation was made concerning the dependence of transformation temperatures, softening temperatures and thermal expansion coefficients of Si-As-Te glasses on composition. Transformation temperatures, Tg, are in the range from about 110 to 368°C, and increase with increasing silicon content and decrease with increasing tellurium content. Temperatures of initial deformation under load, i.e., softening temperatures, Ts, are within about 125 to 425°C and exhibit the same dependence on composition as in the case of Tg. Average linear thermal expansion coefficients at temperatures from room temperature to Tg, αl and from Tg to Ts, αh, are in the range (0.8-2.1)×10-5cm/cm/°C and (1.3-6.2) 10-5cm/cm/°C, respectively. In contrast to the dependence of Tg and Ts on composition, αl and αh decrease with increasing silicon content and increase with increasing tellurium content. For the glasses of a given atomic ratio of silicon to arsenic, both Tg and Ts increase linealy with increasing the concentration of covalent bonds per unit volume, [v], and the following relations are obtained: When the (Si/As) atomic ration is 1.50, Tg=97.19[v]×102-441.4, Ts=112.06[v]×102-506.3. When the (Si/As) atomic ratio is 0.67, Tg=78.49[v]×102-350.6, Ts=84.85[v]×102-368.6. When the (Si/As) atomic ratio is 0.25, Tg=51.61[v]×102-201.1, Ts=60.14[v]×102-237.8. The values of [v] in this investigation are in the range from 5.79×10-2 to 8.32×10-2 mole/cm3. Thermal expansion coefficients, αl and αh, decrease linearly with increasing the concentration of covalent bonds, regardless of the (Si/As) atomic ratio αl×105=-0.4725[v]×102+4.826, αh×105=-1.4976[v]×102+14.616. From the above relations, the following values are estimated for amorphous tellurium: Tg=35±4°C, Ts=43±3°C, αl=(2.54±0.13)×10-5cm/cm/°C and αh=(7.38±0.28)×10-5cm/cm/°C.