© 2017 Elsevier B.V. Hollow metal nanoparticles were produced from a low-melting point alloy, by preventing oxidation of molten metal during fabrication. Molten metal droplets were generated in the water above it by disintegrating bubbles in the molten metal, resulting in the fabrication of metal nanoparticles, accompanied by cooling of the water phase. The hollow structure of the metal nanoparticles was theorized to have occurred due to the Kirkendall effect during oxidation. With the method of applying ultrasonically generated gas-microbubbles, solid/hollow particles were selectively generated by changing the gas supply from oxidizing to non-oxidizing.