The dynamics of the glass transition in Se75Te21Sb3 chalcogenide glass was studied under non-isothermal measurements using differential scanning calorimetry (DSC). The experimental result of the kinetic glass transition phenomenon, at different heating rates (5-40 K/min), was analyzed on the basis of the relaxation process occurring in the transition temperature range. The activation energy of the glass transition was determined using an advanced isoconversion kinetic methods as well as from the heating rate dependence of the glass transition temperature. The fragility index m of the glass was estimated from the measurements of the activation energy of the relaxation process, which characterizes the glass transition. Moreover, the isoconversional kinetic analysis of the experimental data show that the activation energy of glass transition process is varying with the degree of transformation (and hence with temperature) from the glassy to the super cooled phase. (C) 2013 Elsevier B.V. All rights reserved.