Three polymers functionalised with diiron carbonyl units, PVC–Fe-A, -B, and -C, were prepared using commercially available polymer PVC (polyvinyl chloride). PVC–Fe-A resulted from the reaction of the reduced form of a diiron complex, [Fe2(μ-S)2(CO)6], with PVC, whereas PVC–Fe-B and PVC–Fe-C were, respectively, prepared by reacting PVC–N3, the polymer functionalised with azide groups by substitution of the chloride of the polymer, with two diiron complexes, [Fe2(μ-SCH2C
CH)2(CO)6] (1) and [Fe2(μ-SnBut)(μ-SCH2C
CH)(CO)6] (2, nBut = –CH2CH2CH2CH3), via “click chemistry” under the catalysis of CuI. Those polymers were characterised using infrared spectroscopy (IR), scanning electron microscopy (SEM), and thermal gravimetric analysis (TGA). Film electrodes were assembled using a spin-coating technique by casting a mixture of the functionalised polymer, MWCNTs (multi-wall carbon nanotubes), and Nafion onto the surface of a vitreous carbon electrode. The assembled electrodes exhibited electrochemical responses and catalysis on proton reduction in a medium of acetonitrile-acetic acid with a positive shift in reduction potential by over 400 mV compared to the precursor diiron complexes (1 and 2).