The catalytic reaction between carbon monoxide and nitrous oxide has been studied on MnO from 493 to 573 K and on Co3O4from 383 to 493 K. The apparent activation energy on MnO was 130 ± 4 kJ mol−1, while for Co3O4, a change from 31 ± 4 to 105 ± 4 kJ mol−1was observed at 450 K. The rate-controlling step for the catalytic reaction on MnO was associated with the surface reaction between carbon monoxide and nitrous oxide in a manner similar to that previously reported for NiO, while for Co3O4, the rate-determining step was related to the formation of an intermediate surface carbonate. The changes inEAmay be a consequence of the surface reaction proceeding via a concerted redox reaction in the low temperature region and then to a stepwise mechanism at higher temperatures resulting from the presence of structurally and energetically different forms of the intermediate surface carbonate.