The temporal decay of the oxidation of methane (CH4-O-2 reaction) over palladium supported on silica is determined experimentally at different temperatures, comparing the results with those of various classical models which show the behavior of the adsorbed phase as the cause of the phenomenon. This effect is visualized through Monte Carlo simulations of the CH4-O-2 reaction on a mixed lattice whose partial poisoning, due to the configuration of the OH groups on the surface of the adsorbate, is translated into a gradual decay of the reaction's activity.