In this study the electro oxidation of the C-2 alcohols ethanol and ethylene glycol is investigated in acidic and alkaline environment by means of cyclic voltammetry chro noamperometry and differential electrochemical mass spectrometry (DEMS) It is shown that while in acidic medium both alcohols exhibit a comparable electrochemical perfor mance in alkaline medium the current densities for ethylene glycol in cyclic voltammetry and chronoamperometry are substantially higher This signifies that ethylene glycol is more active and the poisoning effect on platinum in alkaline medium is less severe With DEMS it is shown that the oxidation of ethylene glycol in cyclic voltammetry leads to a significant formation of carbon dioxide, indicating bulk oxidation to carbon dioxide For ethanol carbon dioxide formation is only observed at a marginal extent in the potential region where adsorbed carbon monoxide is oxidised This leads to the assumption that carbon dioxide is formed from ethanol adsorbates and is not a product of bulk oxidation (C) 2010 Professor T Nejat Veziroglu Published by Elsevier Ltd All rights reserved