The activation energy (E) of the glass transition and the heating-rate dependence of the glass transition temperature (T-g) of amorphous Se thin film were determined using differential scanning calorimetry (DSC) technique. Non-isothermal measurements were performed at different heating rates (12-40 K/min). Variation of the activation energy was confirmed by the application of five isoconversional methods. These methods showed that the glass transition activation energy is not constant but varies with the degree of conversion (alpha) and hence with temperature (T). The observed temperature dependence of the activation energy is consistent with the free volume model of the glass transition. (C) 2010 Elsevier B.V. All rights reserved.