The fabrication of spherical particles has been of great their interest due to their interesting functionalities. Colloidal spheres of dielectric amorphous materials such as polystyrene and SiO₂ are commercially available. Solution-based self-assembly is also an important approach for the fabrication of spherical particles, although most of the particles are structurally unstable spheres composed of nanoparticle aggregates. Our group previously developed a method for reactive fabrication of B₄C submicrometer spheres by pulsed laser irradiation of boron nanoparticles in organic solvent using a focused laser beam with relatively low fluence. Inspired by this work, we have further developed a novel and versatile fabrication method for submicrometer spherical particles utilizing instantaneous high temperature generated by laser irradiation. Submicrometer spherical particles are obtained by unfocused pulsed laser irradiation onto raw CuO nanoparticles (Fig.).