A process for olefin metathesis is disclosed. The process involves contacting a feedstock comprising a first olefin and a second olefin having a carbon number at least two greater than that of the first olefin with a catalyst comprising a tungsten component on a refractory oxide support, e.g. silica at metathesis conditions to provide a product olefin having an intermediate carbon number between that of the first and second olefin. The catalyst is characterized in that it is first pretreated with hydrogen followed by treatment with ethylene.