The effect of gaseous carbon monoxide on the hydrogenation of acetylene over Ni supported on MgAl2O4 in the presence and absence of zinc dopants has been investigated. Both carbon monoxide and zinc inhibit activity to a considerable extent. Carbon monoxide also lowers the selectivity to ethane substantially. Zinc causes some reduction in selectivity in the absence of carbon monoxide but only at very high conversions when it is present. (C) 2011 Elsevier B.V. All rights reserved.