Hydrogenation of lower alkenes such as ethylene, propylene, and 1-butene proceeded over gallium oxide (Ga2O3). The rate of the hydrogenation was faster in the order of ethylene >> propylene > 1-butene over Ga2O3. Ga2O3 also showed the activity for hydrogenation of 1,3-butadiene where 1,4-addition of hydrogen to 1,3-butadiene mainly took place to give 2-butenes as main products. The formation rate of hydrogenated products depended on the amounts of H-2 and alkenes adsorbed on Ga2O3. This implies that the hydrogenation proceeds on the basis of the Langmuir-Hinshelwood mechanism. (C) 2012 Elsevier B.V. All rights reserved.