The precursor and its formation kinetics were investigated using isotopes of ethanol with supporting calculations using GAUSSIAN09. The major products were CH2OH, C2H5, and ethylene. At temperatures exceeding 900 degrees C, carbon monoxide was also formed, but as less than 20% of the total product. The synthesis of CH2OH and C2H5 were reasonably explained by theoretical calculations; however, the synthesis of ethylene could not be explained by examination of the activation energy. However, if we assumed a specific dissociation order, the activation energy decreased owing to the dissociation of a hydroxyl radical, which was consistent with experimental results. (C) 2014 Elsevier B.V. All rights reserved.