The electrochemical behavior of lead dioxide and synthetic boron-doped diamond thin film electrodes (BDDs) has been studied in acid media containing 4-chlorophenol (4-CP) by bulk electrolysis under different experimental conditions. In order to quantify the electrochemical activity of a given electrode, for the electrochemical oxidation of organic compounds (4-CP), the current efficiency of the anodic oxidation has been normalized taking into consideration mass-transport limitations. The normalized current efficiency (phi) has been defined as the ratio between the current efficiency of the investigated anode to the current efficiency of an ideal anode which has a very fast oxidation rate, resulting in a complete combustion of organics to carbon dioxide. The results have shown that even if the complete combustion of 4-chlorophenol has been achieved at both lead dioxide and boron-doped diamond anodes, the latter give higher f. The difference in reactivity of the electrogenerated hydroxyl radicals on the anode surface, has been proposed to explain the high f values obtained using boron-doped diamond anodes.