SnO 2 films elaborated by sol–gel method were irradiated with reactor neutron. The irradiations were made at a temperature of about 40°C, with fast neutron fluences (E n >1.2MeV) up to 9.6×10 17 ncm −2 . The induced defect has been studied by electrical, optical and structural measurements. The electrical measurements show that the resistivity rapidly increases with increasing fluences up to 3.2×10 17 ncm −2 and remains constant for higher fluence (>6.4×10 17 ncm −2 ). The optical measurements show a small decrease of the optical band gap with increasing fluences. From the X-ray diffraction patterns, it was found that the crystallinity and grain size are reduced.