The invention relates to a process for preparing a catalyst which involves (a) preparing a paste having a uniform mixture of at least one alkaline earth metal carbonate; a liquid medium; a silver bonding additive; and, at least one extrusion aid and/or optionally a burnout additive; (b) forming one or more shaped particles from the paste; (c) drying and calcining the particles; and, (e) impregnating the dried and calcined particles with a solution containing a silver compound. The invention also relates to a process for preparing an olefin oxide comprising reacting a gas composition containing an olefin having at least two carbon atoms with oxygen in the presence of the catalyst composition obtained by the process of this invention.