Critical features of the potential energy surface for the S(N)2 identity exchange reaction F- + CH3F --> FCH3 + F- have been examined using high-quality ab initio quantum chemical techniques. Geometric structures, vibrational frequencies, and relative energies for the separated reactants, ion-molecule complex, and S(N)2 transition state have been determined at various levels of theory by employing Gaussian basis sets ranging in quality from TZ(+(d,p) to [13s8p6d4f,8s6p4d](+) and accounting for electron correlation by means of both coupled-cluster techniques [CCSD and CCSD(T)] and Merller-Plesset perturbation methods [MP2-MP4-(SDTQ)]. The final predictions for the vibrationally adiabatic complexation energy and intrinsic activation barrier are Delta E(w) (F- + CH3F --> [F- CH3F]) = -13.6 +/- 0.5 kcal mol(-1) and Delta E(*) ([F-.CH3F] --> [FCH3F](-dagger)) = 12.8 +/- 1.5 kcal mol(-1), respectively, placing the net S(N)2 barrier 0.8 kcal mol(-1) below, separated reactants. Remarkably, this intrinsic activation barrier for fluoride exchange thus appears to lie within 1 kcal mol(-1) of that for the chloride analog reaction, at variance with the view that F- is intrinsically less reactive than Cl- S(N)2 displacement reactions. To facilitate comparisons among halide identity exchange rates, the bimolecular rate coefficient (k(obs)) for the title reaction has been estimated by employing statistical microcanonical variational RRKM theory with the predicted spectroscopic and thermodynamic data. Within this model k(obs) is 1.5 x 10(-11) cm(3) s(-1) at 300 K and displays a negligible temperature dependence over a wide range.