An exclusive trace of CH₄ direct carboxylation with CO₂ by a stepwise technology was investigated using in-situ FT-IR spectroscopy. The results showed that CH₄ was dissociated to atomic hydrogen and M-CH_x species on catalyst surface when it was first introduced in the system, then CO₂ was inserted into the intermediate to direct carboxylate. Finally, the subsequent adsorption of CH₄ provided active hydrogen for the species of previous surface reaction, thus leading to the formation of the product. It was also found that the first introduction of CO₂ on the surface of the “clean” catalyst might likely react with surface H species, which had an irreversible effect on the catalytic activity of CH₄.