Metal complexes of niobium(V) with 3-substituted-4-amino-5-mercapto-1,2,4-triazole Schiff bases have been synthesized in dry chloroform under a nitrogen atmosphere. They were characterized by elemental analysis, molar conductance, electronic, infrared, 1H-NMR spectroscopy and thermal studies. Parameters, such as energy of activation (Ea), enthalpy (DH#), entropy (DS#) and Gibbs energy (DD#), were computed from the thermal decomposition data. Based on the spectral and thermal studies, a coordination number of seven is proposed.