The relaxation behaviour has been studied of a bulk chalcogenide glass of composition (GeSe2)70(GeTe)15(Sb2Te3)15 prepared by water-quenching or slowly cooling the molten alloy and which was subjected to several thermal treatments. Heat capacity measurements by differential scanning calometry have demonstrated that the undercooled obtained by heating the glass above the glass transition is an an equilibrium state and that slow cooling from this state gives glasses which relax when they are annealed in the glass transition temperature range. The enthalpy and entropy differences between each annealed glass and the undercooled liquid were taken as properties sensitive to the relaxation induced in the glass. These relaxation processes were found to be governed by a distribution of activation energies. The corresponding activation energy spectra characterizing the relaxation processes at three temperatures in the glass transition region were obtained. Their peak energy ranges between 1.4 and 1.6 eV. These values are too high to be related to the elimination pair defects but they are of the order of the bond energies between the constitunts atoms of the glass and therefore the relaxation could be due to the breaking and rearrangement of these bonds in the glassy structure. © 1988.