A new conducting film derived from the complex [Fe (diaphen) À reduction in an ethanol/water solution. Electrocatalysis is centered at the p 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 mM to 417 mM and the LOD was 19.5 mM.