Ethanol is converted into 1-butanol over alkali earth metal oxides and modified MgO catalysts (1-20% yield). The MgO catalyst exhibits the highest reaction activity and 1-butanol selectivity amongst the catalysts studied. Reaction of various intermediates (acetaldehde, crotonaldehyde, crotylalcohol, butanal) and butanol over MgO (1 bar, 450degreesC) revealed that the dimerisation reaction does not proceed primarily through the aldol condensation reaction. The reaction is proposed to proceed through a mechanism (Yang and Meng) in which a C-H bond in the beta-position in ethanol is activated by the basic metal oxide, and condenses with another molecule of ethanol by dehydration to form 1-butanol. (C) 2003 Elsevier B.V. All rights reserved.