Abstract:C20 Guerbet alcohol was synthesized from n-decanol over Ni-Al alloy catalyst, KOH catalyst, and Ni-Al alloy catalyst with KOH, respectively. The results indicated that the mechanism of Guerbet reaction over KOH was different from that over Ni-Al alloy catalyst with KOH. The dehydrogenate activity of metal catalyst was promoted by the synergistic effect of Ni-Al alloy and KOH. It was difficult to dehydrogenate n-decanol to form decanal catalyzed by metal catalyst only under normal pressure in liquid phase.