Large crystals of titanium silicalite or intergrowths of intergrown smaller crystals, having a mean particle size greater than 2 m, have been found catalytically effective at commercially reasonable rates for the epoxidation of olefins in the presence of hydrogen peroxide. Crystals synthesized with a silica source having a low sodium content exhibit high levels of production and selectivity. The crystals have a low attrition rate and are easily filterable from a product stream.