The catalytic oxidation of carbon monoxide to carbon dioxide is a key process for respiratory protection, industrial air purification, automotive emissions control, CO clean up in flue gases and fuel cells, stabilization of CO2 lasers, space and deep sea technology. Extensive research has focused on the improvement of catalytic activity at low temperatures. Numerous catalyst systems have been proposed including Pt, Pd, Rh, Ru, Au, Ag, Cu, supported on refractory or reducible carriers or dispersed in perovskites. A well known commercial catalyst formulation for room temperature CO oxidation is based on CuMn2O4 (hopcalite). High-throughput and combinatorial approaches have been applied to the discovery of more efficient CO oxidation catalysts for various applications. The Symyx screening approach is based on a hierarchy of qualitative or semi-quantitative primary screens for discovery of hits and quantitative secondary screens for confirmation and scale up of leads. For CO oxidation, primary screening was carried out in parallel using IR thermography. Multi channel fixed bed reactors equipped with imaging reflection FTIR spectroscopy were used for secondary screening. The screening protocol encompassed mixed metal oxides, supported metals as well as perovskites. Transition metals, in particular Ru and Co, supported on active carbon and high surface area ceria, were found to show high activities for CO oxidation at low temperatures [1-2]. Furthermore, carbon and ceria supported transition metals (including ceria primed active carbon) have the potential to simultaneously remove VOC and NO in addition. [1] G. Streukens et al., “High Throughput Screening of Low Temperature CO Oxidation Catalysts in IR Thermography Reactor”, 4th International Conference on Environmental Catalysis, Heidelberg, Germany, June 5-8, 2005. [2] S. Cypes et al., “High Throughput Discovery of CO Oxidation/VOC Combustion and Water-Gas Shift Catalysts for Industrial Multi-Component Streams”, Topics in Catalysis (2006), in press.