related reagents. Herein, we designed and synthesized the new electrophilic trifluoromethylselenolation reagents, trifluoromethyl selenoxides, which are easy to prepare and easy-to-handle and are not moisture or air sensitive. The selenoxides are successfully applied to metal-free C–H trifluoromethylselenolation of a series of (hetero)arenes.