The thermal dehydrogenation of NH 3 was studied on Ru(1120) using high-resolution electron energy-loss spectroscopy and thermal desorption spectroscopy. Following NH 3 exposure at 85 K, the expected three dehydrogenation steps could be separated, allowing to isolate successively NH 2 , NH and N on the surface. The Ru(1120) surface is highly reactive as indicated by the complete dehydrogenation of NH 3 for exposures up to 0.2 L. During annealing to 300 K both the channels for desorption and dehydrogenation are opened. Following adsorption at 85 K, the obtained nitrogen coverage of 0.11 ML is low, while for dissociative adsorption of NH 3 at 300 K, a maximum coverage of 0.38 ML is achieved, and the stability of NH 2 is increased.