This paper presents the results of the electron paramagnetic resonance (EPR) study of the anion radical formed from 3-nitroacetophenone (C8H7NO3) (3NAP) single crystal, by gamma irradiation. The EPR spectra of gamma-irradiated single crystals of 3NAP have been recorded at 10-degree intervals for different orientations of crystals in a magnetic field, at room temperature. The EPR analysis of gamma-irradiated crystals of 3NAP has shown that the radiation damage center produced by gamma irradiation is the carbon-centered 3NAP anion radical. One-electron reduction of 3NAP results in general bond loosening. The single crystals have been investigated between 120 and 450K. The spectra have been found to be temperature-dependent. The EPR parameters of the 3NAP anion radical have been evaluated.