Department of Chemistry, University of Rajasthan, Jaipur-302 004 Complexation reaction between niobium(V) and 1,6-dihydroxyphenazine has been investigated with a view to isolate the brown complex and to study its stoichiometry on the basis of elemental analysis, ir spectra, magnetic studies and thermogravimetric analysis. Infrared spectra show 1,6-dihydroxyphenazine acting as a tetradentate ligand coordination through oxygen and nitrogen since two oxine functions are present in the structure of the ligand. A possible polymeric structure of the complex involving ligand and anion bridge has been suggested.