Anion-scavenging materials tailored for 99 TcO 4 À trapping are urgently needed for both nuclear-related environmental remediation and management of spent nuclear fuel. For the first time, we report here an ultra-robust imidazolium-decorated covalent organic framework (COF) conjugate fabricated by an ionizing radiation strategy, for efficient capture of 99 TcO 4À . The charged imidazolium moieties are controllably anchored into the channel of the COF by simply adjusting the g-ray dose, thereby leading to tunable ReO 4 À uptake up to 952 mg g À1 with high selectivity and fast kinetics. More importantly, the high porosity and ultra-robust nanofiber structure of the COFs make them ideal packing materials for dynamic column experiments. >99.98% ReO 4 À /TcO 4 À can be efficiently separated and re-collected, even after four adsorptiondesorption cycles, ranking a new record of the elimination rate for ReO 4 À adsorption. The performance of these materials suggests attractive opportunities in practical applications for TcO 4 À removal from the environment and nuclear waste.