The azo reagent 3-((benzothiazol-2-diazenylnaphthalene-2,7-diol was synthesized and characterized by FT-IR, 1H-NMR and 13CNMR spectral techniques. The electrochemical behavior of the azo reagent and its complex with Fe (III) has been studied at glassy carbon disk GCE electrode in different supporting electrolyte at concentration (1M) and scan rate (100mvs-1). Spectrophotometric determination of Iron (III ) is based on the formation of a 2:1 complex with above reagent. The complex has λmax at (576) nm and εmax of( 1.6451*104)L.mol-1.cm-1. A linear correlation (0.1 - 4.0 μg. ml-1) was found between absorbance at λmax and concentration. The effect of diverse ions on the determination of Iron (III) to investigate the selectivity of the method were also studied. The stability constant of the product was (3.098*108 ). The proposed method was successfully applied to the analysis of blood samples