A new method for the growth of high-quality ZnO nanoparticles is presented here; it is a novel, low-cost, and easy operation. This approach, using solid-state heat decomposition at low temperature, allows one to produce ZnO nanoparticles with relatively high dispersivity. The optical properties of the ZnO nanoparticles have been investigated. It is demonstrated that ZnO nanoparticles show strong ultraviolet emission, while the low-energy visible emission is nearly fully quenched at room temperature. This is a result of the high quality of the ZnO. X-ray diffraction patterns reveal that the ZnO nanoparticles have polycrystalline hexagonal wurtzite structure. The Raman spectrum shows a typical resonant multi-phonon form for the ZnO nanoparticles. Similar synthesis routes for other metal oxide nanoparticles may be possible.