Partial oxidation of methane to syngas(POM)over Rh/SiO2 catalyst was investigated using in-situ FT-IR.when methane interacted with 1.0wt%Rh/SiO2 catalyst,it was dissociated to adsorbed hydrogen and CHx species.The adsorbed hydrogen atoms were transferred to SiO2 surface by "spill-over" and reacted with lattice oxygen to form surface-OH species.POM mechanism was investigated over Rh/SiO2 catalyst using in-situ FT-IR.It Was found that CO2 Was formed before CO could be detected when CH4 and O2 were introduced over the preoxidized Rh/SiO2 catalyst,whereas CO Was detected before CO2 Was formed over the prereduced Rh/SiO2 catalyst.