Infrared Fourier Transform Spectroscopy (DRIFTS). In the case of pure NiO, we found that the surface of the support was mainly covered by elemental Ni under reaction condition, where the Ni/NiO x system is responsible for the high activity of Pt-free catalyst. In the case of Pt/NiO, Pt improves the reduction of NiO x towards metallic Ni. In the case of the 1 % Pt/NiO catalysts, the presence of limited amount of Pt resulted in an optimal quantity of oxidized Pt fraction at 673 K showing the presence of a Pt/PtO x /Ni/NiO x mixed phase where the different interfaces may be responsible for the high activity and selectivity towards methane. In the case of pure NiO under reaction condition, small amounts of formaldehyde as well as hydrogen perturbed CO [H n CO (n=1,2)] were detected. However, in the case of 1 % Pt/NiO catalysts, besides the absence of formaldehyde a significant amount of H n CO (n=2-3) was present on the surface responsible for the high activity and methane selectivity.