A process for the oxidation of carbon monoxide to carbon dioxide in the presence of elemental nitrogen with minimal oxidation thereof which comprises combining the carbon monoxide with a predetermined amount of oxygen containing gas to give at least 1% stoichiometric excess of oxygen for the oxidation of carbon monoxide to carbon dioxide and passing the resulting mixture over a ceramic catalyst of the following empirical formula at a temperature between about 100.degree. C and about 1,000.degree. C;w.sub.k X.sub.n J(1-k-n).sup.ZO (3.+-.m)WhereinW is Zirconium, Tin or Thorium or mixtures thereof;X is an alkaline earth metal or mixture thereof;J is scandium, ytrrium, a rare-earth element or mixture thereof;Z is a metal of the first transition series or a mixture thereof, at least 0.01% of said metal having an oxidation state other than +3;k is a number having a value between 0 and about 0.1;m is a number having a value of from 0 to about 0.26; andn is a number having a value from 0 to about 0.51, provided when n has a value of 0, k has a value between 0 and about 0.05.