Abstract: This article studied the relation of the incubation necessary for the directed oxidation of the molten Al-Mg-Si alloy at high temperature in the air with the content of Mg and Si in the parent alloyby the TG experiments. It was proved that the directed oxidation of Al-Mg-Si alloy is consistent with Arrhenius formula. The relation of the nominal activation energy of the bulk oxidation of the aluminum melt with the Mg and Si content of the parent alloy was studied also.