A carrier for a catalyst useful for the epoxidation of an olefin which comprises an inert, refractory solid carrier is provided. The carrier has no or little absolute volume from small pores, of less than 1 micrometer, and large pores, of above 5 micrometer. By "no or little absolute volume from small pores of less than 1 micron" it is meant that the pore volume of such pores is less than 0.20 ml/g. By "no or little absolute volume from large pores of above 5 micron" it is meant that the pore volume of such pores is less than 0.20 ml/g. The invention further provides a catalyst useful for the epoxidation of an olefin supported on such a carrier and a process for the oxidation of an olefin, especially ethylene, to an olefin oxide, especially ethylene oxide.