Using the dispersion-corrected density functional theory calculations, the catalytic performance of P-doped graphene with divacancy (P-G(DV)) is examined for the oxidation of CO by O-2 molecule. According to our results, the first step of CO oxidation (CO + O-2 -> CO2 + O*) proceeds via Langmuir-Hinshelwood mechanism with a small activation energy (0.28 eV). The remaining O atom (O*) is then eliminated by another incoming CO molecule with an energy barrier of 0.59 eV. It is found that the orbital hybridization between the O-2-2 pi and CO-2 pi* states in the coadsorbed structure plays an important role for the first step of the CO oxidation. Our result indicates that the low-cost P-GDV can be regarded as an active metal-free catalyst for CO oxidation at room temperature. (C) 2018 Elsevier B.V. All rights reserved.