One mild multiple emulsions was used for the fabrication of hollow polystyrene (PS) spheres. Polystyrene was dissolved in a volatile organic solvent to form the O phase, then an aqueous phase containing a surfactant was transferred into above phase to form an oil-in-water (W-in/O) emulsion, followed by addition of W-in/O emulsion in the external W-out phase, and solvent evaporation. Final product with diameter of 150 mu m, surface roughness of 30 nm, and sphericity of 98.0% was obtained. The possible influences on the formation of PS hollow sphere were also discussed. Crown Copyright (C) 2010 Published by Elsevier B.V. All rights reserved.