Platinum coated with films of poly-paradimethoxybenzene (poly-pDMB) and with platinum particles dispersed on the film has been investigated for formic acid electrooxidation using in situ Fourier Transformed Infrared Reflectance spectroscopic techniques. In this work, techniques such as Single Potential Alteration Infrared Reflectance spectroscopy and Subtractively Normalized Interfacial Fourier Transformed Infrared Reflectance spectroscopy have been used to detect and identify adsorbed species, intermediates and reaction products during this process. Oxidation of formic acid leads to the rapid formation of strongly adsorbed species, acting as poisons on the surface of the electrode; however, the presence of a poly-pDMB film significantly modifies the adsorption and oxidation process. The poisoning phenomenon is drastically decreased and the complete oxidation of formic acid to CO2 is clearly observed when the film is present. The polymer changes the electrooxidation process by modifying the way the formic acid molecule approaches the electrode surface. Polymer and polymer-metallic particles modified platinum electrodes showed better electroactivity than bare platinum electrode. In former cases, a decrease in poisoning was observed. (c) 2006 Elsevier B.V. All rights reserved.