The influence of the axial ligand on the Co–pyridine bond distance and on the extent of the pyridine dissociation was investigated in a series of cobaloximes featuring different inorganic ligands (X = Cl, N3, NO2) together with the corresponding metallorganic derivatives: ClCo(dmgH)2Py (1), N3Co(dmgH)2Py (2), NO2Co(dmgH)2Py (3), EtCo(dmgH)2Py (4), ClCo(dpgH)2Py (5) and EtCo(dpgH)2Py (6). The molecular structures of NO2Co(dmgH)2Py (3), EtCo(dmgH)2Py (4) and EtCo(dpgH)2Py (6) were determined by X-ray crystallography. The analysis of the bond distances in the X–Co–Py fragment showed an increment of about 0.1 Å in the Co–Py bond distance when passing from the chloride derivatives 1 or 5 to the ethyl derivatives 4 or 6. In the dmgH series, the Co–Py bond distance increases in the order 1