The concentration behavior of the thermal expansion coefficient of glasses in the system GaX 2 -GeX 2 -Sb 2 X 3 (X = S, Se) has been studied in two sections. Parameters characterizing the relaxation properties of the glasses have been calculated on the basis of the Tool-Narayanaswamy theory from experi mental temperature dependences of the thermal expansion coefficient in the softening range. Temperature dependences of the viscosity have been calculated under the assumption of equal free activation energies for the relaxation and viscous flow.