The electrochem. behavior of PbO2 and synthetic B-doped diamond thin film electrodes (BDDs) was studied in acid media contg. 4-chlorophenol (4-CP) by bulk electrolysis under different exptl. conditions. To quantify the electrochem. activity of a given electrode, for the electrochem. oxidn. of org. compds. (4-CP), the current efficiency of the anodic oxidn. was normalized taking into consideration mass-transport limitations. The normalized current efficiency (j) was 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 oxidn. rate, resulting in a complete combustion of orgs. to CO2. The results showed that even if the complete combustion of 4-CP was achieved at both PbO2 and BDD anodes, the latter give higher j. The difference in reactivity of the electrogenerated hydroxyl radicals on the anode surface, is proposed to explain the high j values obtained using B-doped diamond anodes. [on SciFinder (R)]