Using competition kinetic methodology, absolute rate constants for bimolecular hydrogen abstraction from a variety of organic substrates in solution have been obtained for the n-C4H9CF2CF2., n-C4F9., and i-C3F7. radicals. Fluorine substitution substantially increases the reactivity of alkyl radicals with respect to C-H abstraction, with the secondary radical being most reactive. A wide range of substrate reactivities (5200-fold) was observed, with the results being discussed in terms of an interplay of thermodynamic, polar, steric, stereoelectronic, and electrostatic/field effects on the various C-H abstraction transition states. Representative carbon-hydrogen bond dissociation energies of a number of ethers and alcohols have been calculated using DFT methodology.