In this study, the interaction between methane and well-defined Pt single crystal surfaces at room temperature was studied by electrochemical method and in situ FTIR spectroscopy. The results demonstrated that, amongst the three basal planes of Pt single crystal (Pt(111), Pt(110), Pt(100)), only Pt(100) can activate methane, in which the dissociation of methane could be detected at potentials above 0.0 V (vs.SCE) (Fig.1). At potential range between 0.0 V and 0.15 V, methane may be mainly dehydrogenated to produce spices like CO/COH, resulting in the decrease of Hudp on Pt(100). At potentials above 0.15 V, such spices can be further oxidized to form CO2. In situ FTIR spectroscopy studies indicated that methane can be oxidized to CO on Pt(100) surface and the CO mainly bound to hollow sites, moreover no oxidation product was detected on Pt(111) and Pt(110). DFT calculations show that on Pt(111) and Pt(100), the most stable surface species both are CH*, while on Pt(100) the most stable one is CH2*. On Pt(100), CH* prefers to be oxidized by O* with the lowest barrier being 0.4 eV. However, on Pt(110) and Pt(111), CHx* oxidation is much more difficult since the coupling between the carbon species and OH* is as high as 1.03 eV and 0.85 eV, respectively.