CuS　hollow　spheres　were　quickly　synthesized　under　mild　conditions　with　spherical　aggregates　of　Cu2O　nanoparticles　as　sacrificial　templates.　The　mechanism　involved　in　the　synthesis　process　has　been　studied　using　transmission　electron　microscopy,　high-resolution　transmission　electron　microscopy,　scanning　electron　microscopy,　X-ray　diffraction,　thermal　gravimetry,　and　Fourier　transform　infrared　spectra.　The　results　show　that　the　formation　of　loose　aggregates　of　Cu2O　nanoparticles　is　the　key　to　the　fast　synthesis　of　hollow　spheres　at　low　temperature.　The　thickness　of　the　shell　can　be　controlled　easily　by　adjusting　the　aggregation　degree　of　the　Cu2O　nanoparticles.　©　2009　American　Chemical　Society.