Using the electron spin resonance (ESR) technique, the kinetic and spectroscopic properties of free radicals generated by gamma radiation in oleaster (Elaeagnus angustifolia L.) fruits were investigated. For ESR measurements, skin parts of unirradiated (Group-A) and gamma-irradiated (Group-B) oleaster fruits were used. While the ESR spectrum of the Group-A samples consisted of a singlet signal at g = 2.0032 ± 0.0002, two cellulosic signal components were observed in the low (g = 2.0205 ± 0.0002) and high (g = 1.9861 ± 0.0002) field regions of this singlet signal in Group-B sample. A model containing three free radicals was used to determine spectroscopic parameters of radiation-specific radicals. The stability at room temperature and detailed kinetic behaviors of the radiation-specific signals were investigated. Results show that gamma irradiation induces free radicals in oleaster fruits, and these radicals can be used to identify gamma irradiation process. Graphic abstract: [Figure not available: see fulltext.].