SiO2 hollow spheres with movable Fe3O4 core were obtained by exposing the pre-synthesized Fe3O4/SiO2 particles (with an adsorption interlayer of ethylene glycol) under the irradiation of electron beam inside transmission electron micrograph (TEM). In the formation process, the evaporation of adsorbed ethylene glycol and the evolution of amorphous SiO2 layer played important roles, and that should be attributed to the high temperature and trapped charges induced by the irradiation of electron beam. This work provided a new route to obtain particles with movable core structure and extended the applications of electron beam. (C) 2011 Elsevier Ltd. All rights reserved.