Multi-valence Cu x O has been demonstrated to have high activity in the low-temperature selective catalytic reduction of NO x with NH 3 (NH 3 -SCR). Here, Cu x O was loaded onto activated semi-coke (ASC) for SCR, which has shown satisfactory low-temperature SCR activity. By virtue of the reduction property of carbon, the valence of Cu was regulated by simply adjusting the calcination temperature. The high concentration of Cu + generated from the reduction of CuO by ASC during calcination can collaborate to form Cu 2+ /Cu + circulation. After systematic characterization by XPS, H 2 -TPD, and NH 3 -TPR, it is revealed that abundant acidic sites and surface reactive oxygen species are formed on the surface of the catalysts. Further investigation with in situ DRIFTS confirms that the NH 3 -SCR over the as-prepared CuO|Cu 2 O-ASC catalysts simultaneously follows the Langmuir-Hinshelwood (L-H) and Eley-Rideal (E-R) pathways, attributed to the synergistic effects of Cu 2+ and Cu + .