High-level ab initio calculations of the potential energy surface for the F(2P)+CH3(X2A2″) reaction show that the CH 3 F intermediate can be formed without a barrier and then dissociate via four product channels, including F+CH 3 , HF+CH 2 ( 1 A 1 ), H 2 +CHF, and H+CH 2 F. RRKM and transition state theories have been applied to compute rate constants and branching ratios of the F+CH 3 /CH 2 +HF/CHF+H 2 /CH 2 F+H products at various collision energies and temperatures. H+CH 2 F are predicted to be the major reaction products (except at low temperatures) followed by H 2 +CHF. The H abstraction mechanism leading to HF+CH 2 ( 3 B 1 ) over a low, 1.4kcal/mol, barrier is also important at high collision energies and temperatures.