High yields of acrylic acid are obtained in the partial oxidation of acrolein on multicomponent oxides containing mainly Mo, V, W and Cu. The system can be described by use of a simple network of two parallel and one consecutive reaction. The basic mechanism of the partial oxidation is still not known. However, if oxygen spillover is involved, the addition of an oxygen donator to the multicomponent catalyst should influence the kinetics. Different antimonates, considered as oxygen donors and mixtures (1:1 by weight) of these antimonates with the original catalyst have been studied, The pure antimonates showed no activity. In the mixed catalysts a marked effect was observed thus giving a strong hint that oxygen spillover is playing a major role in the partial oxidation of acrolein on oxidic catalyst.