Mesoporous silica microspheres (MSM) approximately 1.0 mu m in diameter were prepared by the hydrolysis and condensation of tetraethoxysilane (TEOS) under the presence of dodecylamine (DDA) as a molecular template and catalyst in ethanol-water solution. Isolated MSM were obtained in a narrow range of experimental conditions, which were experimentally correlated by the linear relationship between the molar ratio of ethanol and TEOS and that of DDA and TEOS. Isolated MSM modified with thiol groups were also prepared under similar experimental conditions, by co-condensation of TEOS and 3-mercaptopropyltrimethoxysilane (MPTMS). The thiol-functionalized MSM (SH-MSM) adsorbed silver ions from an aqueous solution. Asymmetrical polystyrene film, in which the SH-MSM were self-assembled on the surface of the water phase side of the film, was obtained by spreading and polymerizing of styrene monomer with dispersed SH-MSM on the water surface. The polymer film containing SH-MSM also effectively adsorbed silver ions.