The structural stability and guest occupation behavior of argon-loaded hydroquinone (Ar-HQ) clathrates after γ-irradiation were investigated through a suite of diffraction, spectroscopic, and thermogravimetric methods. Ar-HQ, synthesized via the gas-phase reaction method at 12 MPa for 10 days showed complete structural transformation from pure α-form into β-form HQ clathrates. Upon γ-irradiation up to 50 kGy, we found that the crystal structure of Ar-HQ clathrates remained intact with only a marginal change in the Ar storage capacity. These results provide useful guidelines to evaluate the potential of host-guest clathrate compounds as nanostructured container-media of radioisotope gases.