The catalytic oxidation of carbon monoxide has been studied over trans
ition metal oxides in the absence and presence of platinum. A characte
ristic activity pattern was observed in both cases, with platinum redu
cing the temperature at which oxidation was initiated by between 20 an
d 200 K. The results show that platinum-metal oxide interactions are i
mportant in the system. These appear to involve the reaction of carbon
monoxide adsorbed on the metal with oxygen associated with the metal
oxide lattice.