Vanadium-antimony oxide selective oxidation catalysts are prepared using a novel peroxide-based sol-gel synthesis procedure. The catalysts are prepared by reaction of soluble peroxovanadium complexes with antimony trioxide under refluxing conditions. The procedure produces a stable colloidal sol of microcrystalline rutile vanadium antimonate having an average particle size of 6.7 nm. Drying the sol gives a gel consisting of pure rutile vanadium antimonate having the vanadium/antimony ratio of about 1/1, consistent with the stoichiometry of the well-characterized crystalline phase V 8/9 Sb 8/9 0 2/9 O 4 . The driving force for the formation of this phase is the redox reaction between a V 5+ peroxo complex and Sb 3+ oxide to form the V 4+ ,Sb 5+ -containing vanadium antimonate. The peroxide-based solgel preparation procedure allows formation of vanadium antimonate under milder conditions than previous synthesis methods that rely on heating of mixtures of vanadium and antimony oxides.