A catalyst for the epoxidation of an olefin comprising a carrier and deposited on the carrier, silver, a promoting amount of one or more promoters selected from the group consisting of alkali metals and rhenium and a promoting amount of nickel, wherein the nickel is added as a nickel compound or nickel complex during the initial impregnation along with the silver and other promoters; including a process for preparing the catalyst; a process for preparing an olefin oxide by reacting a feed comprising an olefin and oxygen in the presence of the catalyst; and a process for preparing a 1,2-diol, a 1,2-diol ether, a 1,2-carbonate, or an alkanolamine.