The mechanism of the multi-channel reaction H + CH3CH2Br is studied by QCISD(T)/ 6-311+G(2df, 2p)//BH&H-LYP/6-311G(d, p) level. The rate constants are evaluated using canonical variational transition state theory (CVT) with a small-curvature tunneling correction ( SCT) over a range of temperatures 220-2000 K. The calculations show that in the four reaction channels, i.e., bromine-, alpha-hydrogen and two beta-hydrogen abstractions, the bromine abstraction channel is most prominent and hydrogen abstraction channels appear to be probable only at high temperatures. Agreement between theory and experiment is good. (C) 2008 Published by Elsevier B.V.