The tailoring of the pore surface chemistry of activated carbon fibers is shown to be an effective method for increasing the removal efficiencies of various contaminants under a fixed bed configuration. An oxidation treatment with nitric and sulfuric acids resulted in a significant increase in the adsorption capacities and breakthrough times. The adsorption kinetics were described by a homogeneous surface diffusion model. Although the effective diffusion coefficients were actually reduced by the oxidation process, the improvement in equilibrium adsorption capacities more than compensated, to result in the overall improved breakthrough times.