The mechanism of dissociative evaporation was used for a quantitative interpretation of the kinetics and mechanism of thermal decomposition of the azides of Na, K, Pb, Ag, Tl, Ba, Sr and Ca. Decomposition is assumed to proceed by way of gasification of all primary products, including free metals, with nitrogen evolving partially as free atoms and, in the case of lead azide, in the form of neutral N-3 molecules as well. The actual decomposition pathways were chosen based on the best fit between the calculated and experimental values of the absolute decomposition rates and the activation energies. An analysis of published mass spectrometric studies into the thermal decomposition of NaN3 and TlN3 has confirmed partial evolution of nitrogen in the form of free atoms. The mechanism and specific features of the UV-chemiluminescence and chemi-electron emission accompanying the decomposition of azides has been interpreted in terms of this approach.