GaS compound is an n type semiconductor which belongs to AIIIBVI materials class. Elementary packings are formed of four atomic planes arranged in the order S – Ga – Ga –S. Inside packings strong ionic-covalent forces act, while between packings weak forces of van-der-Waals type act. The chemical bonds anisotropy allows the obtaining of parallel plates by single crystals cleavage. The crack between packings facilitates the intercalation of different atoms and molecules. The single crystals doping and intercalation with heterogeneous chemical elements expand the physical properties of this material. By high temperature thermal annealing of GaS crystals in Zn vapour are obtained composed materials consisting of both base material and ZnS crystallites. In this work are analysed the luminescent properties of both untreated GaS crystals and GaS crystals thermally annealed in Zn vapour. PL spectra were analysed in the 80-300K temperature range and contain both GaS and ZnS characteristic bands. The GaS-ZnS composite is a material with wide PL, which covers the wave length range from NIR frontier (~720 nm) up to UVC. At the same time with formation of recombination levels, that determines the photoluminescent emission efficiency, in the material obtained by thermal annealing are formed electron trapping levels. Energetic characteristics of these states were determined by TSL measurements. Structural defects generated by both ZnS crystallites and atoms intercalated between elementary packings form energy levels localized near the band gap centre of micro and nanocrystalline GaS compound.