The oxidation of CO plays important roles in control of automotive emi
ssion and theoretical research. Noble metals, as CO oxidation catalysts, have go
od activity and long service life. But with the deficiency of noble metal resour
ces and the escalation of their price, it is necessary to search for alternativ
es for noble metal catalysts. More attention is being paid to the roles of rare
earth in CO oxidation catalysts. Noble metals, nonnoble metals and rareearth
catalysts were reviewed in this article.