The magnetically supported heteropolyacid nanophase catalysts with the core-shell structure, in which the heteropolyacid molecules are embedded in the silica nanocoating supports, have successfully been obtained by a sol-gel incorporation technique rather than the impregnation method. The nanocomposites are composed of magnetic Fe3O4 nanophase cores, the interior silica nanocoatings as the anticorrosion layers and the exterior heteropolyacid-silica coatings. The catalytic performance of the resulted catalysts is comparable with that of pure heteropolyacids in esterification reaction of ethanol and acetic acid; in addition, the resulted catalysts can be used repeatedly without significant decrease of activity. (C) 2010 Elsevier B.V. All rights reserved.