AbstractWe have studied the effect of vibrational mode activation in the CF3radical on the bromine abstraction reaction; CF3+ Br2→ CF3Br + Br. Excess vibrational energy resides in the symmetric modes of the radical after 248 nm photolysis of the parent molecule, CF3I. Our data indicate that the hot radicals react no faster than thermalized CF3, and may actually have a lower cross‐section for reaction. Dynamical factors that result in poor coupling of the vibrational energy to the reaction coordinate, as well as other similar considerations, could be responsible for the experimental observations. In addition, we have made an independent determination of the rate for the bromine abstraction reaction of (1.08 ± .13) × 1012s−1c