Low-dimensional cuprous nitride (Cu₃N) was synthesized by nitridation (ammonolysis) of cuprous oxide (Cu₂O) nanocrystals using either ammonia (NH₃) or urea (H₂NCONH₂) as the nitrogen source. The resulting nanocrystalline Cu₃N spontaneously decomposes to nanocrystalline CuO in the presence of both water and oxygen from air at room temperature. Ammonia was produced in 60% chemical yield during Cu₃N decomposition, as measured using the colorimetric indophenol method. Because Cu₃N decomposition requires H₂O and produces substoichiometric amounts of NH₃>, we conclude that this reaction proceeds through a complex stoichiometry that involves the concomitant release of both N₂ and NH₃. This is a thermodynamically unfavorable outcome, strongly indicating that H₂O (and thus NH₃ production) facilitate the kinetics of the reaction by lowering the energy barrier for Cu3N decomposition. The three different Cu₂O, Cu₃N, and CuO nanocrystalline phases were characterized by a combination of optical absorption, powder X-ray diffraction, transmission electron microscopy, and electronic density of states obtained from electronic structure calculations on the bulk solids. The relative ease of interconversion between these interesting and inexpensive materials bears possible implications for catalytic and optoelectronic applications.