Reactions between adsorbed atomic nitrogen and ethylene on Rh(lll)have been investigated by temperature-programmed reaction spectroscopy (TPRS), secondary ion mass spectrometry (SIMS), and work function measurements. Coadsorption of a small amount of ethylene to 0.10 monolayer of atomic nitrogen results in the formation of a surface cyanide species, which is detected by SIMS through the Rh2CN+ cluster ion. Cyanide formation has been followed by measuring the decrease of the atomic nitrogen and carbon coverages and the accompanied increase in the CN coverage in temperature-programmed SIMS experiments. The CN formation kinetics is described by a preexponential factor and an activation energy of 10(11+/-1) s(-1) and 111 +/- 10 kJ/mol, respectively. In the absence of surface hydrogen, CN groups are stable up to similar to 700 K. CN decomposition results in reaction-limited desorption of Nz with a maximum at 800 K and is described by a preexponential factor and an activation energy of 10(13+/-1) s(-1) and 210 +/- 15 kJ/mol. Coadsorption of large amounts of ethylene to 0.10 monolayer of N-ads results in the desorption of almost all nitrogen in the form of HCN between 500 and 700 K. Cyanogen was also observed as a reaction product although the selectivity was small, 3% at maximum. Work function measurements indicate that surface cyanide is present as a negatively charged species on the Rh(lll) surface.