The molecular modeling studies were carried out to elucidate the mechanisms of NO heterogeneous reduction with the presence of CO using density functional theory (DFT). The zigzag and armchair configurations composed with several aromatic ring clusters were selected as the carbonaceous surfaces. The reaction energies and activation energies were calculated by the location of transition states and intermediates in the potential energy surface (PES). Over the temperature range of 298.15 K-1800 K, the reaction rate constants were figured out by means of conventional transition state theory (TST). According to the degree of CO participation in reactions, two primary pathways are obtained leading to final products in which one generates N-2 and CO2 (CO addition), and the other generates N2O (without CO). Based on the results of the comparison between two channels, the specific effect of CO is promoting, which is reflected in the rate and the number of active sites. The calculations indicate that NO heterogeneous reduction is susceptible to be affected by the nature of active sites and the presence of CO. (C) 2017 Elsevier Ltd. All rights reserved.