Oscillatory instabilities are ubiquitous in many electrocatalytic reactions. In the case of the electrocatalytic oxidation of small organic molecules, oscillating electrode potential and reaction current are very often found under different experimental conditions. Most of the experimental studies are devoted to C1 molecules such as formic acid and methanol, and very few reports concerning C2 compounds are available, in spite of their technological relevance as potential fuels. We report in this letter the observation of fast potential oscillations during the electrooxidation of ethylene glycol on platinum and in alkaline media. Oscillations were studied under galvanostatic control, and oscillation frequencies as high as 16.8 Hz were observed. To the best of our knowledge, those potential oscillations are the fastest ones ever reported for the electro-oxidation of small organic molecules, and we named them beta oscillations in reference to the taxonomy employed to classify brain rhythms. Oscillations were observed at different temperatures, and the system's dynamics was found to be rather insensitive to temperature, in contrast to that observed under non-oscillatory regime.Due to properties such its good reactivity, low toxicity, and high specific energy, ethylene glycol (EG) has been considered a promising organic molecule to be electrooxidized in low temperature fuel cells [1][2][3]. The electrooxidation of EG on platinum is a complex process that involves different adsorbed and soluble intermediates and might result in a variety of partially oxidized products. Overall, EG can be oxidized to different aldehydes and carbonyl acids, and when the C-C bond remains intact, oxalate is the most oxidized specie (eight electrons). If there is scission, the oxidation reaction can reach CO 2 (that react with OH − ions resulting in CO 3 2− ) and other partial C1 intermediates, such as formate and formaldehyde. Hauffe and Heitbaum [4] studied the electro-oxidation of EG on platinum and in aqueous KOH and observed that alcohol release, in average, eight electrons per molecule. The authors suggested that the major oxidation product was oxalate. Christensen and Hamnett used in situ FTIR [5] and showed that in acid media, the major products are glycolic acid and CO 2 , whereas in alkaline media, glycolate, oxalate, and carbonate are the major products.Besides those mechanistic complications, the electrooxidation of ethylene glycol may also render chemical instabilities in the form of oscillatory kinetics. In contrast to other small organic molecules [6], there are very few results on the oscillatory dynamics of the electro-oxidation of EG [7,8]. We report in this letter a rather peculiar aspect of the electocatalytic oxidation of EG on platinum and in alkaline media, namely the fastest oscillations ever reported for the electro-oxidation of small organic molecules.A platinum sheet with 0.26 cm 2 of electroactive area was used as working electrode. The counter electrode was a high area platinized platinum mesh. All potentials we...