The properties and olefin metathesis activity of molybdena - alumina, molybdena - silica - alumina and molybdena - silica catalysts prepared by anchoring of MoO2(acac)(2) complex were compared. The speci. c activity obtained for molybdena - silica - alumina system is higher than that of molybdena - alumina and molybdena - silica catalysts. This statement concerns also the catalysts treated with tetramethyltin.