Crystallization studies using differential scanning calorimetry under non-isothermal conditions with the samples heated at different rates (5, 10, 15 and 20 K/min) have been reported and discussed. The effect of Bi addition to the Se-Te matrix on the mechanism of crystal growth has been investigated. The glass transition temperature is found to increase with increase in heating rate as well as with the addition of bismuth. The activation energy for glass transition and that for crystallization have been determined using the Kissinger equation and the Matusita equation. Thermal stability and glass-forming tendency have also been studied. Theoretical calculations of the viscosity have been done using data of heating rate dependence of glass transition temperature and the peak crystallization temperature.