Superconductivity in Al/Al2O3 interface

•Al/Al2O3 interface was formed by surface oxidation of Al foil.•Magnetic susceptibility and electrical resistance of the interface was studied.•Superconductivity at ∼ 65 K of the Al/Al2O3 interface was observed.•The superconducting interface is instable under normal conditions.

Metastable superconductivity at Tc ≈ 65 K has been observed in Al foil subjected to special oxidation process, according to the ac magnetic susceptibility and electrical resistance measurements. Comparison of the ac susceptibility and the dc magnetization measurements infers that the superconductivity arises within the interfacial granular layer formed during the oxidation process between metallic aluminum and its oxide.