Abstract: A tin(IV) oxide dispersion is prepared by peptising metastannic acid with amine peptising agent such as n-butylamine or cyclohexylamine. The dispesion may be a sol or an intermediate convertible to a sol, and may include other components such as metal oxides or their precursors, e.g. one or more of a high surface area alumina and transition metal oxides such as copper(II) oxide and chromium (VI) oxide. The dispersion may be converted to a gel and then to a ceramic, optionally after the sol has been contacted with a substrate, for example to produce a catalyst. Further coatings may be applied to produce a catalyst comprising a mixture of tin(IV) oxide and chromium(VI) oxide on the substrate which may be effective as an oxidation catalyst and useful in the treatment of vehicle exhaust emissions.