The adsorption of CO and NO and their coadsorption on the Rh(100) surface are discussed in terms of extended Hiickel/tight binding calculations. Experimentally, it is not easy to resolve the linear and bent forms of NO, and for this reason our calculations serve not only as an examination of the proposed adsorption geometries but also as means to investigate the NO dissociation mechanism. This dissociation is believed to be the fundamental step in the CO/NO reaction. The adsorption site and geometry are discussed for several NO chemisorptions. In addition, a discussion of the CO/NO reaction for the proposed adsorption of NO is presented. From this analysis, it is clear that predissociation of NO into atomic components can lead to recombination producing the desired reaction products, CO2 and N2. Furthermore, the coadsorbate interactions can lead directly to the desired products. © 1990, American Chemical Society. All rights reserved.