The crystallization kinetics of the chalcogenide glass Se0.8 Te0.2 was studied by means of differential scanning calorimetry. The variation in partial area (X) with temperature (T) revealed that the transition from the amorphous to the crystalline phase occurs in two dimensions. Activation energies were determined for both the glass transition (Et) and the crystallization (Ec). Et was calculated from the variation in Tg with the heating rate (a ). Ec was determined by three different methods: (i) variation in X with T, (ii) variation in Tp with a , and (iii) variation in Tc with a . Et and Ec have values of161.01±2.75 and 84.75± 8.21 kJ/mol, respectively.