Uniform-sized and monodispersed boehmite core-shell and hollow spheres have been successfully synthesized using a template-free solvothermal route. The experimental parameters Such as reaction duration, the trisodium citrate amounts and solvents are shown to play important roles in the formation of the AlOOH core-shell and hollow spheres. X-ray diffraction, Fourier transform IR, thermal gravimetric analysis, N(2) adsorption/desorption, scanning electron microscopy, transmission electron microscopy, and high-resolution TEM were used to characterize the products. The results show that the prepared polycrystalline hollow spheres are composed of well-aligned AIOOH nanowires and have an orthorhombic structure. Finally, a dissolution-renucleation mechanism was proposed for the formation of boehmite hollow structures. Crown Copyright (C) 2009 Published by Elsevier Ltd. All rights reserved.