The analysis of the molecular structure and spectral properties of succinimide can be used as a reliable tool in understanding all interactions between this molecule with the other chemicals. For this reason, we first examined the conformational variety of succinimide in free state through an energy minimization calculations using the spartan 08 software. This preliminary calculation confirmed that free succinimide molecule has only one stable conformer at room temperature and the dipole moment and energy values of this conformer are 2.221 Debye and -360.779 Hartree, respectively. The optimized geometry of the conformer was then obtained at B3LYP/6-311++ G(d, p) level of theory by using the Gaussian 03 software. In the next step of the study, eleven radicals were formed from this one conformer of succinimide by removing an hydrogen atom or changing its location in the molecule. For each radical structure, the corresponding Electron Paramagnetic Resonance (EPR) parameters were calculated using the DFT/B3LYP method and TZVP basis set and then they were compared with the corresponding experimental values. The "g" value (EPR parameter) calculated in this study for the model radical (Rad 6) is 2.00388 and in good agreement with the corresponding experimental value (2,00339) previously reported in the literature for the radical form of succinimide.