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Finding transition metal catalysts for effective catalytic conversion of CO to CO2 has attracted much attention. MXene as a new 2D layered material of early transition metal carbides, nitrides, and carbo-nitrides is a robust support for achoring metal atoms. In this study, the electronic structure, geometries, thermodynamic stability, and catalytic activity of MXene (Mo2CS2) supported single noble metal atoms (NM = Ru, Rh, Pd, Ir, Pt and Au) have been systematically examined using first-principles calculations and ab initio molecular dynamic (AIMD) simulations. First, AIMD simulations and phonon spectra demonstrate the dynamic and thermal stabilities of Mo2CS2 monolayer. Three likely reaction pathways, LangmuirHinshelwood (LH), Eley-Rideal (ER), and Termolecular Eley-Rideal (TER) for CO oxidation on the Ru1- and Ir1 @Mo2CS2 SACs, have been studied in detail. It is found that CO oxidation mainly proceeds via the TER mechanism under mild reaction conditions. The corresponding rate-determining steps are the dissociation of the intermediate (OCO-Ru1-OCO) and formation of OCO-Ir1-OCO intermediate. The downshift d-band center of Ru1- and Ir1@Mo2CS2 help to enhance activity and improve catalytst stability. Moreover, a microkinetic study predicts a maximum CO oxidation rate of 4.01 x 10 2 s-1 and 4.15 x 10 3 s-1 (298.15 K) following the TER pathway for the Ru1- and Ir1 @Mo2CS2 catalysts, respectively. This work provides guideline for fabricating and designing highly efficient SACs with superb catalyts using MXene materials.