Аннотация:The kinetics and mechanism of stepwise transformations during bulk isothermal crystallization of semiconductor glasses As2Se3Snx (x = 0.26, 0.40, 0.55) in the temperature range of 210-310 °C have been investigated by the methods of 119Sn NAGRS, XRD, density, microhardness and electrical conductivity of quenched samples. It was found that the primary fine-dispersed SnSe phase initiates heterogeneous nucleation and two-dimensional crystal growth of the secondary main phase As2Se3.