The technique of using an accelerated beam of protons to generate characteristic X-rays from elements is shown to be particularly useful for analyzing catalysts. The information comes from within the first few micrometers of the surface, so all elements in this region, i.e., the catalytic elements as well as trace impurities in the support, are detected. The technique is highly sensitive for all the main catalytic elements (down to at least 10-12 g absolute and 10-6 relative concentration) and is rapid, taking typically only a few minutes to obtain a sample spectrum. Unlike X-ray production by electron beam irradiation, advantage can be taken of the fact that the information may be rendered quantitative simply by preparing the sample in the form of small (<2 μm) particulates: 3 MeV protons lose typically <2% of their energy in traversing such a particle. No chemical information is obtained, but the technique, by virtue of its special features, is well suited for use in conjunction with other near-surface analytical techniques. © 1976.