Thermal stability Of Cu-0..3(SSe20)(0.7) chalcogenide glass was investigated by differential scanning calorimetry (DSC). The level of stability for first SSe20 and second Cu2Se phases of the present glass was estimated by evaluation of the glass criteria: Deitzel first glass criterion, DeltaT, Hruby criterion, H-r, and Saad and Poulan weighted thermal criteria, H' and S. The values of these criteria were obtained based on characteristic temperatures such as: the glass transition temperature, T-g, the onset temperature of crystallization, T-c, the temperature corresponding to the maximum crystallization rate, T-p and the melting temperature T-m. It was found that the values of DeltaT, H-r, H' and S parameters for the first SSe20 phase is smaller than that of the second Cu2Se phase. That indicates a greater thermal stability of second Cu2Se phase. The stability order at different heating rates is Cu2Se > SSe20 as revealed also by thermal K-r(T) criterion. (C) 2004 Elsevier B.V. All rights reserved.