This work considers the oxidation of ammonia (NH3) by selective catalytic oxidation (SCO) over a Pt-Pd-Rh cordierite monolith catalyst in a tubular fixed-bed flow quartz reactor (TFBR) at temperatures between 423 and 623 K. A Pt-Pd-Rh cordierite monolith catalyst was prepared by incipient wetness impregnation with aqueous solutions of H-2 PtCl6, Pd(NO3)(3) and Rh(NO3)(3) that were coated on cordierite substances. The catalysts were characterized using XRD, PSA and SEM. The experimental results show that around 99.0% NH3 removal was achieved during catalytic oxidation over the Pt-Pd-Rh cordierite monolith catalyst at 623 K with oxygen content of 4%. N-2 was the main product in the NH3-SCO process over the Pt-Pd-Rh cordierite monolith catalyst. These results also verify that the Pt-Pd-Rh metals on cordierite monolith surfaces, resulting in the formation of catalytically active sites at the metal-support interface in the reduction of NH3 in the process. (C) 2010 Elsevier B.V. All rights reserved.