The surface chemistry of hydrocarbon carboxylic acids has been compared with that of perfluorinated carboxylic acids on the Ag(110) and Ag(111) surfaces. The hydrocarbon acids adsorb reversibly on the clean silver surfaces. On Ag(110) their desorption energies increase linearly with increasing alkyl chain length (n) and are given by the expression DeltaE(des) = 10.6 + 0.9n kcal/mol. The surface chemistry of the perfluorinated acids is quite different from that of the hydrocarbon acids in the sense that they deprotonate to form perfluorocarboxylate species on both Ag(110) and Ag(111) surfaces. The perfluorocarboxylates are stable until the surface temperature reaches similar to 620 K, at which point they decompose yielding desorption Of CO2 and other decomposition fragments. On both Ag surfaces 2,2,2-trifluoroacetate (CF3CO2) generated by deprotonation of 2,2,2-trifluoroacetic acid (CF3CO2H) has been identified by its vibrational spectrum. The fact that fluorinated acids deprotonate on the Ag surfaces while the hydrocarbon acids desorb during heating indicates that fluorination lowers the deprotonation barrier, DeltaE(dep)(double dagger), to the point that it is lower than the desorption energy, DeltaE(des).