A synergistic effect of Fe(II) and copper oxide (CuO) was observed on the degradation of acetaminophen (ACT) in the presence of O-2. The results showed that 89% of ACT (50 mg/L) was degraded within 6 h by 10 mM Fe2+ with 5 g/L CuO powder at pH 3.0, among which about 30% of ACT was mineralized. The sorbed Fe(II) on the CuO surface which is more reactive than the dissolved Fe(II) was capable of reducing both Cu(II) and O-2. The resulting Cu(I) significantly accelerated the destruction of ACT by serving as an electron-mediator between the sorbed Fe(II) and O-2. In addition, the hydrogen peroxide (H2O2), hydroxyl radical ((OH)-O-center dot) and superoxide anion radical (O-center dot(2)) were identified as the main reactive oxygen species (ROSs) generated in Fe(II)/CuO suspension by Electron paramagnetic resonance (EPR) technique and quenching studies; however, only (OH)-O-center dot was found to have caused the decomposition and mineralization of ACT. First O-center dot(2) was generated by reduction of O-2 through a one-electron transfer pathway. Then the generated O-center dot(2) mediated the production of H2O2, which further decomposed into (OH)-O-center dot by Cu(I)- and Fe(II)catalyzed Fenton reactions. The effects of Fe(II) concentration, CuO dose, solution pH and the degradation pathway were investigated, respectively. (C) 2017 Published by Elsevier B.V.