Copper nanoparticles have been prepared by the solvated metal atom dispersion (SMAD) method. Oxidation of the SMAD prepared copper colloids resulted in Cu@Cu(2)O core shell structures (7.7 +/- 1.8 nm) or Cu(2)O nanoparticles depending on the reaction conditions. The nano Cu, Cu@Cu(2)O core shell, and Cu(2)O particles were found to be catalytically active for the generation of hydrogen from ammonia-borane either via hydrolysis or methanolysis reaction.