Abstract: A catalyst for the oxidation of propylene, said catalyst having the composition represented by the following formulaMo.sub.a W.sub.b Bi.sub.c Fe.sub.d A.sub.e B.sub.f C.sub.g D.sub.h O.sub.xwhereinA represents at least one element selected from the group consisting of nickel and cobalt,B represents at least one element selected from the group consisting of alkali metals, alkaline earth metals and thallium,C represents at least one element selected from the group consisting of phosphorus, arsenic, boron and niobium,D represents at least one element selected from the group consisting of silicon, aluminum and titanium,a, b, c, d, e, f, g, h, and x respectively represent the atomic ratios of Mo, W, Bi, Fe, A, B, C, D, and O,a is from 2 to 12,b is from 0 to 10,the sum of a and b is 12,c is from 0.1 to 10.0,d is from 0.1 to 10.0,e is from 2 to 20,f is from 0.005 to 3.0,g is from 0 to 4,h is from 0.