We report the results of structural studies of samples of nanocrystalline tin oxide, zirconia, magnesia, alumina and silica, prepared by sol-gel techniques (including the addition of silica to restrict grain growth) and high-energy ball milling. XRD, EXAFS/YANES and MAS-NMR analyses were used to characterise the materials. EXAFS showed that nanocrystals of ZrO2 and SnO2 prepared by sol-gel methods are highly crystalline, consistent with previous EXAFS studies of sol-gel prepared nanocrystalline oxides [A.V Chadwick, M.J. Pooley, K.E. Rammutla, S.L.P. Savin, A. Rougier, J. Phys.: Condens. Matter, 15 (2003) 43 L; A.V Chadwick, G.E. Rush, in Nanocrystalline Metals and Oxides: Selected Properties and Applications, (Kluwer, New York), (2002), p. 133.]. In contrast, the sol-gel prepared SiO2 appeared amorphous, even after prolonged heating at 1200 degrees C. The EXAFS of the ball-milled samples showed clearly attenuated signals that cannot be attributed solely to particle size. Ball milling of quartz crystals (which have a simple Q(4)) first broadens the NMR line and then generates Q(3) and then Q(2) lines indicating the generation of amorphous materials in the samples.