We have carried out ethanol conversion reactions on the MoO3 under the pulse infrared irradiations (period = 2 s) with several wavelengths emitted from free-electron-laser. We found a piece of evidence to show the dependence of activities in the ethanol conversion rate on the infrared wavelengths. When the wavelength was tuned to 967 cm(-1), which corresponded to the absorption frequency of 0.167 nm Mo=O bond, C2H5OH was converted mainly to CH4 with CH3CHO as a minor product while no reaction occurred at 1200 cm(-1) where no resonant vibration mode Of MoO3 was present. The reaction products were different from those produced in thermal reactions.