The electrochem. behavior of a synthetic B-doped diamond thin film electrode (BDD) was studied in acid media contg. phenol using cyclic voltammetry and bulk electrolysis. In the potential region of H2O stability direct electron transfers can occur on BDD surface resulting in electrode fouling due to the formation of a polymeric film on its surface. During electrolysis in the potential region of oxygen evolution, complex oxidn. reactions can take place due to electrogenerated hydroxyl radicals. Electrode fouling is inhibited under these conditions. Depending on the exptl. conditions, the electrogenerated hydroxyl radicals can lead to the combustion of phenol or to the selective oxidn. of phenol to benzoquinone. The exptl. results also were compared to a theor. model that permits the prediction of the evolution with time of phenol concn., during its combustion, or during its selective oxidn. to benzoquinone. [on SciFinder (R)]