The oxidation of carbon monoxide on different Pt-Sb2O4 catalysts has been studied in the temperature range 60 < THETA/degrees-C < 140. The oxygen partial pressure was kept constant at 60 mbar, the partial pressures of carbon monoxide varied in the interval 0.01 < P(CO)/mbar < 10. The results show that, in contrast to Pt-SnO2 catalysts, a synergistic effect seems to be improbable. No indications of a special effect of oxygen spillover (e.g. remote control) could be observed.