Electrochemical oxidation of p-nitrophenol (PNP) and p-methoxyphenol (PMP) at Bi-doped PbO2 electrodes under thin-layer condition was studied by Fourier transform infrared spectroelectrochemistry (FTIR) as a function of electrode potential and the initial concentration of organic compound. The results show that complete mineralization of the organic species was achieved at potentials more positive than 1.4 V vs. SCE and the mineralization process was not determined by the concentration of phenols. From the electric charge transferred during thin-layer controlled potential electrolysis, we found that PNP and PMP electrooxidation follow Langmuir–Hinshelwood kinetics.