A silver catalyst (I) for the oxidn. of ethylene (E) to ethylene oxide (EO) is claimed, contg. 1-25 wt.% Ag on a highly-porous heat-resistant support, and produced by impregnating the support in one or more stages with an Ag-contg. soln. and precipitating the Ag on the particles; the novelty is that the concn. of Ag in the particles is non-uniform, with a markedly greater concn. at the outer (geometric) surface and in the layers adjacent to the surface than in the interior. USE/ADVANTAGE - (I) is useful for the gas-phase oxidn. of (E) with oxygen (claimed). W.r.t. prior-art catalysts, (I) has improved activity and selectivity.