Coated catalysts having an inert support material with an outer surface and a coating of active catalyst containing tungsten, vanadium and molybdenum plus optionally one or more of Fe, Mn, Cu, Sn, Sb, Cr, Ce, U, Co, Ni, Zn, Mg or mixture thereof have been found to be especially effective catalysts for the production of unsaturated acids from the corresponding unsaturated aldehydes, for example, acrolein is oxidized to acrylic acid using these catalysts. The catalysts give a very low exotherm, very high single pass yields of the desired acid and reduce the undesirable by-products.