This article presents a facile, effective, mild synthesis process for well-defined hollow spheres by using cationic polystyrene (PS) submicro-particles as templates. In this approach, the cationic PS templates can be first prepared via emulsifier-free polymerization by using the cationic monomer 2-(methacryloyloxy) ethyltrimethylammonium chloride as comonomer, then, the silica shells from the sol-gel process of tetraethoxysilane were coated on the surfaces of template particles via electrostatic interaction, finally the PS was dissolved in situ by modification of the reaction conditions in the same medium to form monodisperse hollow silica spheres with controlled shell thickness. Fourier transform-infrared spectroscopy, thermogravimetric analysis, Brunauer-Emmett-Teller, transmission electron microscopy, and scanning electron microscope measurements were used to characterize these hollow silica spheres. (C) 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 13321338, 2010