High-level ab initio calculations of the potential energy surface for the F((2)p) + CH3(X(2)A(2)") reaction show that the CH3F intermediate can be formed without a barrier and then dissociate via four product channels, including F + CH3, HF + CH2((1)A(1)), H-2 + CHF, and H + CH2F. RRKM and transition state theories have been applied to compute rate constants and branching ratios of the F + CH3/CH2 + HF/CHF + H-2/CH2F + H products at various collision energies and temperatures. H + CH2F are predicted to be the major reaction products (except at low temperatures) followed by H2 + CHF. The H abstraction mechanism leading to HF + CH2(B-3(1)) over a low, 1.4 kcal/mol, barrier is also important at high collision energies and temperatures. (c) 2005 Elsevier B.V. All rights reserved.