Inorganic oxides with high surface area find versatile applications in fields ranging from catalysis to medicine. In this study, we have investigated the potential of two mesoporous aluminum oxides with high surface area, MSU-X and Al-TUD-1, as adsorption materials for Mo-99/Tc-99m generators utilized in nuclear medicine. For this purpose we have studied the molybdenum adsorption kinetics and isotherms of these materials and we have compared them with acid activated aluminum oxide (AA) that is conventionally applied in generators. The results reveal that MSU-X and Al-TUD-1 have much better adsorption performance than AA in terms of kinetics and maximum adsorption capacity. The best results have been obtained for Al-TUD-1 reaching maximum adsorption capacity of 112mgg(1), more than two times the adsorption capacity of AA materials. Furthermore, 4050% of Tc-99m could be removed from all sorbents in a single elution with negligible loss of Mo-99. Aluminum breakthrough has been found to be higher than the accepted limit in all tested materials when high molybdenum concentrations have been used, indicating that the aluminum oxides may need to be specially pre-treated in order to prevent contamination of the Tc-99m eluate.