Abstract: A catalyst for oxidation of olefins which has a composition of the general formulaMo.sub.a Bi.sub.b Fe.sub.c Co.sub.d Ni.sub.e Q.sub.f R.sub.g X.sub.h Z.sub.i O.sub.jwherein Q is at least one element selected from Au and Nd; R is at least one elemet selected from K, Rb, Cs and Tl; X is at least one lement selected from P, As and B; Z is at least one element selected from Ce, Ti, Te, Zn, Ge, Sn, Cr, Ga, La, In, Al, Cd, Pd, Mn, V, W, Pb, Nb, Ag, Zr, Cu and U; a, b, c, d, e, f, g, h and i respectively represent the numbers of Mo, Bi, Fe, Co, Ni, Q, R, X and Z atoms, and when a is 12, b is 0.1-10, c is 0.5-40, d is 0-12, e is 0-12 with the proviso that the sum of d and e is 0.5-15, f is 0.1-8, g is 0.01-5, h is 0-5, i is 0-12; and j is the number of oxygen atoms which satisfies the atomic valences of the other elements.