[en] In this paper, double-bond-modified fibrous mesoporous silica (F-SiO₂-K) microspheres were prepared first, and then grafted with poly (4-vinylpyridine) (P(4-VP)) in 4-VP or its methanol solution initiated by γ-ray irradiation to obtain pyridine modified mesoporous silica (F-SiO₂-VP) microspheres. The Fourier transform infrared spectroscopy (FTIR) and thermal gravimetric analysis (TGA) results indicated the successful grafting of P(4-VP). The degree of grafting (D_G) of P(4-VP), which was calculated from TGA curves, increased with the monomer concentration and the absorbed dose, however reached a maximum value at a moderate dose rate. The adsorption ability of F-SiO₂-VP for U(VI) in nitric acid solution was investigated. The results show that the adsorption capacity is related to the concentration of nitric acid and the D_G of F-SiO₂-VP, and reaches a maximum of 163 mg/g. The adsorption kinetics fits the pseudo-second-order model, and the adsorption isotherm of F-SiO₂-VP fits the Freundlich model at low U(VI) concentrations and the Langmuir isotherm well at high U(VI) concentrations. (authors)