We report here the first example of a homogeneous first row transition-metal-based catalyst which is active for dehydrogenation of ammonia-borane, H3NBH3, a promising chemical hydrogen storage material. Addition of ammonia-borane to an active catalyst formed in situ from the reaction of Ni(cod)(2) and 2 equiv of an appropriate N-heterocyclic carbene (NHC) rapidly evolves hydrogen at 60 degrees C. Using a gas burette to quantify the gas evolved, 29 of a possible 31 mL of H-2 for 3 equiv of H-2 was produced, equating to > 2.5 equiv of H-2 from ammonia-borane. Kinetic isotope effects of deuterated derivatives of ammonia-borane suggest that both N-H and B-H bonds are being broken in the rate-determining step(s).