The thermal dissociation of three cobalt(II) azido complexes of the type CoL4(N-3)(2) where L = 4-benzoyl-, 4-ethyl-, and 5-hydroxypyridine, have been studied by thermogravimetry (TGA and DTA) and IR spectroscopy, The three complexes form an intermediate 1 : 2 complex which explodes in the case of the 4-benzoylpyridine complex. Hydrogen bonding plays a significant role in the stability and decomposition of the 1.4 and 1 : 2 complexes in the case of 3-hydroxypyridine ligand.