A new conducting film derived from the complex [Fe (diaphen)(3)](2+), (diaphen=5,6-diamino-1,10-phenanthroline) was electropolymerized by cyclic voltammetry onto a glassy carbon electrode. Poly-[Fe(II) (diaphen)(3)] was studied by cyclic voltammetry, SEM, UV-vis and micro-Raman spectroscopy. Poly-[Fe(II) (diaphen)(3)] shows electrocatalytic activity in HSO(3)(-) reduction in an ethanol/water solution. Electrocatalysis is centered at the pi ring of phenanthroline. Rotating disk electrode studies showed a 0.117 V/dec Tafel slope, suggesting an EC process where the electrochemical process is the determining step. The chemical step was studied by UV-vis spectroelectrochemistry. Amperometric behavior showed a linear range between 47.5 mu M to 417 mu M and the LOD was 19.5 mu M.