The oxidation of α-D(+)-glucose on a platinum electrode in 0.1 M NaOH was investigated by in situ Fourier transform infrared reflection-absorption spectroscopy in the potential range, -0.76 to +0.46 V vs. Hg/HgO, OH-. The surface adsorbates were found to involve linear CO and bridged CO. The linear CO persisted on platinum in the entire potential range with gradual shifts to higher frequencies, ca. 70 cm-1/V while the bridged CO disappeared as the electrode potential reached -0.05 V. The oxidation products were carboxylic acid and CO2. A potential excursion up to +0.46 V was found to cause a pH swing of more than 8 in the spectroelectrochemical thin layer due to the great extent of glucose oxidation. This was evident from the gluconic acid and CO2 peaks in the IR spectra.