The adsorption, decomposition of CH3 and its reactions with CO2 were followed by means of Fourier transform infrared spectroscopy combined with mass spectrometry. Methyl radicals were produced by the pyrolysis of azomethane. Absorption bands, observed at room temperature adsorption, were attributed to adsorbed CH3 and CH3O species. The decomposition of adsorbed CH3 in vacuum started above 400 K and was accelerated by CO2. In the study of the interaction of methane with titania, activated in different ways, we found no convincing spectroscopic evidence for the activation of methane at 300 K.