Process for forming multi-component oxide catalysts. According to the invention the key catalytic phase of the catalyst is preformed and the elements of the host-catalyst phase are added together or separately. The key catalytic phase contains a molybdate or a tungstate of Bi, Te, Sb, Sn Cu or mixtures thereof. A representative catalyst is 50% [Bi2Mo3O12] 1/2 [K0.1Ni2.5Co4.5Fe3P0.5Mo10.5 Ox] + 50% SiO2 In the production of this catalyst a preformed bismuth molybdate slurry is added to a host-catalyst slurry. The mixture was then dried, calcined, ground and calcined once again.