This work describes the oxidation of ammonia (NH3) at temperatures between 423 and 673 It by selective catalytic oxidation (SCO) over a Pt-Rh nanocomposite catalyst that was prepared by the co-precipitation of H2PtCl6 and Rh(NO3)(3) in a tubular fixed-bed flow quartz reactor (TFBR). The catalysts were characterized using TEM, XRD, PSA, and CV. The experimental results reveal that at a temperature of 673 K and an oxygen content of 4%, approximately 98% of the NH3 was removed by catalytic oxidation over the Pt-Rh nanocomposite catalyst. N-2 was the main product of the NH3-SCO process. The Pt-Rh nanocomposite-induced cytotoxicity to the human lung cell line, MRC-5, was tested, and cell survival was determined using 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl )-2 H-tetra-zolium (MTS) analysis in vitro. These results demonstrated that the Pt-Rh nanocomposite catalyst is only weakly cytotoxic to human lung cells. (C) 2011 Elsevier B.V. All rights reserved.