<p>The surface of liquid aluminum in the absence of oxygen and after reacting with different levels oxygen gas has been investigated by performing molecular dynamics simulations based on embedded atom model potential. Results in the oxygen-free condition indicate that liquid aluminum exhibits surface-induced layering. The surface is randomly close-packed at the highest possible packing density. Upon exposure to oxygen, oxygen atoms get adsorbed and embedded within the top layers, relaxing the surface. The layered surface transforms into Al-rich amorphous alumina layer. The first amorphous alumina to form is Al₅O. With increasing oxygen content, O/Al ratio increases, resulting in further relaxation. When the O/Al ratio approaches 1.0, Al-rich <i>γ</i>-alumina nucleates and grows epitaxially underneath the amorphous surface alumina. The change in molar surface area with surface relaxation is nonmonotonic. Implications of these results on the surface tension of partially oxidized liquid aluminum are presented in the paper.</p> Graphical Abstract