[en] This study deals with the effect of thermal annealing on structural/microstructural, thermal and mechanical behavior of pristine Se₈₀Te₁₆Cu₄ and carbon nanotubes (CNTs) containing Se₈₀Te₁₆Cu₄ glassy composites. Pristine Se₈₀Te₁₆Cu₄, 3 and 5 wt%CNTs-Se₈₀Te₁₆Cu₄ glassy composites are annealed in the vicinity of glass transition temperature to onset crystallization temperature (340–380 K). X-ray diffraction (XRD) pattern revealed formation of polycrystalline phases of hexagonal CuSe and trigonal selenium. The indexed d-values in XRD patterns are in well conformity with the d-values obtained after the indexing of the ring pattern of selected area electron diffraction pattern of TEM images. The SEM investigation exhibited that the grain size of the CNTs containing Se₈₀Te₁₆Cu₄ glassy composites increased with increasing annealing temperature and decreased at further higher annealing temperature. Thermal conductivity, microhardness exhibited a substantial increase with increasing annealing temperature of 340–360 K and slightly decreases for 380 K. The variation of thermal conductivity and microhardness can be explained by cross-linking formation and voids reduction. (paper)