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We report UPS/XPS results for ammonia adsorption and decomposition on a Ni(1 10)-surface. At T < 130 K molecular adsorption of NH 3 is observed to proceed with an initial sticking coefficient of s 0-0.1. Increasing the temperature of the nickel surface above 150 K results in partial dissociation of the adsorbed NH 3 molecules. The intermediate species are tentatively identified by their photoelectron spectra as NH-fragments. At temperatures above 350 K only atomic nitrogen is observed to populate the surface after NH 3-exposures. Our data show a similar reactivity of the Ni(ll0) surface in the NH 3-decomposition reaction as found on iron-single crystal planes. We briefly discuss this result with respect to the negligible activity of nickel as a catalyst for ammonia formation.