We report a comprehensive study of γ-irradiation on optical, electrical, and laser characteristics of pure and transition-metal doped single and polycrystalline ZnS and ZnSe. Polished pure, Cr-doped, and Ag, Au, Cu, Al, In, and Mn co-doped ZnS and ZnSe crystals after absorption and electro-conductivity characterization were γ-irradiated at doses of 1.28x108 rad at -3°C. Dynamic room temperature absorption studies, electroconductivity measurements, and mid-IR lasing were performed after different exposition times of crystals at room temperature. Cr:ZnSe and Cr:ZnS lasers based on identical γ-irradiated and non-irradiated crystals featured very similar pump thresholds, slope efficiencies, and output powers. New fluorescence band spanning over 1.3-2.1 μm in the γ-irradiated Au:Cr:ZnS was attributed to 3A2→3T2(F) transition of Cr4+ ©2013 Optical Society of America.