Boron nitride (BN) nanotubes having only tens of nanometers; in diameter and open tip-ends were uniformly filled with a MgO2-based material. The crystal structures and chemical compositions of the tubes and filling media were analyzed using high-resolution and energy-filtered electron microscopy, electron diffraction, electron energy loss, and energy dispersion X-ray spectroscopy. A low melting point (similar to88 degreesC) and easy decomposition of the filling inside the tubes under moderate heating, e.g., during in-situ electron irradiation in an electron microscope, and/or just during room temperature aging, may generate a spatially localized oxygen outflow from the nanotubes. The MgO2-filled material is uniquely characterized by a stable oxygen release rate with long release term. Thus the first nanotube-based oxygen generator has been realized.