Hollow spheres of Cu2O with an average diameter of 0.3-0.6 mum have been prepared by a simple reaction between CuO suspension and NH2OH in the presence of deionized gelatin at room temperature. Gelatin played a decisive role as an inhibitor of the direct attack of NH2OH to CuO surfaces and coagulation of the growing Cu2O in producing the hollow spheres. The products were characterized by X-ray powder diffraction, transmission electron microscopy, X-ray photoelectron spectra techniques and UV-visible absorption spectroscopy. The band gap is estimated to be 2.60eV according to the results of optical measurements of the hollow spheres. (C) 2003 Elsevier Science B.V. All rights reserved.