The kinetics of the CN+CH3Br reaction were studied using transient infrared laser absorption spectroscopy to detect CN reactants and HCN products. This reaction has a rate constant of k=(2.20±0.6)×10−12 exp (453±98/T)cm3molecule−1s−1 over the range 298–523K. Hydrogen abstraction to produce HCN+CH2Br is only a minor reaction product, with a branching fraction of 0.12±0.02. Other product channels, including BrCN+CH3, CH2CN+HBr, CH3CN+Br are likely. An upper limit of 0.01 was established for the HBr yield. These results are in qualitative agreement with recent ab initio calculations.