The paper describes part of the results of the first year of the IAEA Coordinated Research Project F23032, Contract № 20567 on “Studying Side-Effects of Gamma Irradiation Treatment for Disinfestation of Cultural Heritage Artefacts”. Calf leather, calf suede and pig skin patterns were selected and analyzed by Scanning electron microscopy (SEM), and Thermal gravimetric analysis (TGA) before and after the gamma-irradiation treatment with 5 kGy, 10 kGy and 15 kGy absorbed doses at low dose rate. The irradiation of the leather materials was performed in the gamma-irradiation facility BULGAMMA based on JS-850 60Co type gamma irradiator at Sopharma JSC. No significant changes in the leather morphology and thermal decomposition were observed as a result of the gamma-irradiation treatment. Conclusions on the applicability of gamma-irradiation treatment for preservation of leather items with insecticide and fungicide doses were done.