Sn(CH3)4/Al2O3 prepared by the deposition of Sn(CH3)4 to alumina which was previously dehydroxylated by heating at 773-1223 K was found to be an active catalyst for the metathesis of alkenes. The catalytic activity greatly depended on the pretreatment temperature of the alumina and the amount of Sn(CH3)4 deposited.