The density functional theory was studied to examine the suggested type of model radicals RI, RII and RIII that have been formed upon gamma-irradiation of single crystals of amphi-chloroglyoxime (ACG). RI, RII and RIII type model radicals were obtained by abstraction of Cl and H atoms from ACG. The possible conformations of these model radicals were obtained using the semi-empirical Austin Model 1 method. Subsequently, hyperfine coupling constants and atomic spin density calculations of these conformations were performed using the Becke-3-Lee-Yang-Parr functional in combination with a split-valence Gaussian basis set. Theoretically calculated values were compared with the experimental values. Calculated isotropic and anisotropic hyperfine coupling constant values of conformations of model radical RII were in good agreement with experimental values. However, the agreement was rather poor in the case of the model radicals RI and RIII. Thus, the findings from the present study clearly suggest that the experimentally observed radical should be the model radical RII.