2-Azidoacetone (N3CH2COCH3) has been synthesized and characterized by a variety of spectroscopic techniques, and the thermal decomposition of this molecule at temperatures in the region 300-1150 K has been studied by matrix isolation infrared spectroscopy and real-time ultraviolet photoelectron spectroscopy. The results show the effectively simultaneous production of six prominent decomposition products: CH2NH, CH2CO, HCN, CO, N-2, and CH3CHO, and several reaction pathways are proposed to account for their formation. Results of ab initio molecular orbital calculations indicate that the primary reaction intermediate is the imine HNCHCOCH3, with the nitrene NCH2COCH3 being a transition state. No experimental evidence was found for the presence of the imine HNCHCOCH3, but mechanistic considerations, and the existence of several weak unassigned IR bands point to the presence of a further decomposition product, which may be CH2NCH3.