Glassy Se70Te30 thin films were thermally evaporated onto chemically cleaned glass substrates. Crystallization kinetics were determined under isothermal conditions. DC conductivity of the investigated film was used as a parameter to calculate the crystallized fraction chi (t) The values obtained for the activation energy of crystallization and the Avrami index were 239.8 +/- 0.5 kJ/mol and 2.21 +/- 0.1, respectively. The non-integer value of the Avrami index indicates that two crystallization mechanisms, one- and two-dimensional growth, are responsible for the crystallization process.