Abstract: The present invention relates to the discovery of a new catalyst and in methods for the preparation of oxidation products such as unsaturated acids, nitriles, and aldehydes by vapor phase oxidation in the presence of the catalyst. The catalyst gives high productivity of desired products over a prolonged period of operation, high selectivity over a prolonged period of operation and prolonged life of the oxidation catalyst system.The catalyst, on a molar basis, has the composition Sb.sub.0-.1 Sn.sub.0-.1 Te.sub..001-1 As.sub.0-1 A.sub.0-1 /Y.sub.12 X.sub.2-12 Sb.sub.0-1 Th.sub..01-1 U.sub.0-2 Si.sub.0-50 -P.sub.0-5 Ox, wherein A is Bi and/or Cd, and X is Co or Fe or both, and Y is Mo or W, or both.