The electrooxidation of ethylene glycol (EG) on a Pt/Vulcan catalyst was investigated over a wide range of temperatures (20-100 degrees C) at 3 bar overpressure and under continuous electrolyte flow by on-line differential electrochemical mass spectrometry (DEMS). Both Faradaic current and the ion current for CO(2) formation were continuously followed during potentiodynamic and potentiostatic measurements. They show pronounced temperature and potential effects on the total reaction rates and on the rate/selectivity for complete oxidation to CO(2). While at room temperature formation of incomplete C(2) oxidation products prevails, complete oxidation to CO(2) becomes increasingly important at higher temperatures and at lower potentials (50% current efficiency for CO(2) formation at 100 degrees C and 0.5 V). This behavior is reflected by a significantly higher barrier for CO(2) formation than for the total reaction, with values of 80 and 50 kJ mol(-1), respectively, at 0.5 V. The implications of these data for the understanding and proper description of the reaction in fuel cell applications and the importance of realistic reaction conditions in model studies for predictions of the reaction behavior under these conditions are discussed. (C) 2009 Elsevier B.V. All rights reserved.