Forced oscillations of the carbon dioxide concn. in a hydrogen feed were applied to the carbon dioxide methanation reaction with simultaneous gas phase and surface anal. The response of the gas phase and surface species to these repeated dynamic conditions show a time shift following the sequence CO2 -> formate -> CO -> methane, but can be modeled by a simple model involving one single adsorbed surface intermediate and a reservoir in equil. with this intermediate. The dynamic behavior of this intermediate is very close to the variation of the IR absorption band assocd. with formate and carbonate species. [on SciFinder (R)]