This study elucidates ammonia (NH3) oxidation by selective catalytic oxidation (SCO) over a Pt-Pd-Rh ternary composite cordierite substrate catalyst in a tubular fixed-bed flow quartz reactor (TFBR) at temperatures of 423-623 K. A Pt-Pd-Rh ternary composite cordierite substrate catalyst was prepared by incipient wetness impregnation with aqueous solutions of H2PtCl6, Pd(NO3)(3) and Rh(NO3)(3) that were coated on cordierite ceramic honeycomb substances. Experimental data indicate that high NH3 reduction activity was achieved during catalytic oxidation over the Pt-Pd-Rh cordierite substrate catalyst at 623 K with an oxygen content of 4%. Notably, N-2 was the predominant product of the NH3-SCO process over the Pt-Pd-Rh cordierite substrate catalyst These experimental results also confirm that an initial high concentration of NH3 influent decreases ammonia removal efficiency. Further, catalysts were characterized by SEM, TGA-DTA, FTIR and TEM. Analytical results indicate that catalytic behavior is associated with the Pt-Pd-Rh ternary composite and cordierite ceramic honeycomb substrate. (C) 2010 Elsevier B.V. All rights reserved.