The surface chemistry of CF3CH2(ad) and CF3CF2CH2(ad) on the Ag(111) surface was studied by temperature-programmed-reaction (TPR) measurements. These species, which are generated on the surface by thermal dissociation of the C-I bond in the corresponding fluoroalkyl iodides, undergo beta-fluoride elimination to give the corresponding fluoroalkenes and adsorbed fluorine. Kinetic parameters obtained from variable heating rate TPR studies show that while the pre-exponential factors for the beta-fluoride elimination reaction in CF3CH2(ad) and CF3CF2CH2(ad) are the same, i.e., 10(14.7+/-0.8) s(-1), the activation energies are considerably different, i.e., 18.1+/-0.9 and 13.9+/-0.7 kcal/mol, respectively. Utilizing the fact that F has a greater electron-withdrawing inductive effect than CF3, we conclude that the charge separation in the transition state is of the form C-delta+...(F delta-). The adsorbed F generated by the beta-fluoride elimination reaction desorbs as AgF at similar to 850 K. Unlike adsorbed alkyl groups, which couple to produce alkanes, the hydrofluoroalkyl groups studied here react by the beta-fluoride elimination pathway, probably due to the increase in the barrier to coupling caused by fluorination at the beta-carbon.