This study evaluated the electrochemical advanced oxidation process (EAOP) using boron-doped diamond (p-Si/BDD) anode in the abatement of the antibiotic norfloxacin (NOR). The influence of the applied current density (i(app)), initial concentration of NOR, sodium sulfate (Na2SO4) concentration and reactor operation conditions were evaluated. The mechanism of NOR oxidation (direct or indirect) was also studied by cyclic voltammetry and chronoamperometry. The results showed that, depending on the i8pp, and the NOR and Na2SO4 concentration, the NOR could be oxidized by direct electron transfer, with the carbon-sp2 impurities on the p-Si/BDD surface, and indirect, by persulfate ions (S2O82-), sulfate (SO4)(-) and/or hydroxyl radicals (HO electrogenerated at the anode surface. When the reactor is operated favoring the electro-generated HO., NOR abatement and chemical oxygen demand (COD) reduction are simultaneous. Conversely, at the time that the reactor is operated favoring the NOR direct oxidation and by S2O82- and SO4-, NOR and COD reduction are not parallel leading to high byproducts formation. Therefore, it is important to know the matrix content (organic and sulfate content), for the correct choice of the operational parameters that will lead to a low byproducts formation.