Previous radial distribution work which we have found reported in the literature has invariably been based on film technique. Our work is entirely based on X-ray spectrometer intensity measurements, Radial distribution (RD) patterns for silica gel and η-aluinina are presented and the correlation with accepted structures for these materials demonstrated. The advantages of spectrometer over film technique are discussed. The entire calculation problem has been programed for the IBM 650 computer, A difference technique which appears very sensitive to small structure changes is described and demonstrated for silica-alumina cracking catalysts. A procedure for identifying systematic errors in the RD pattern is presented.