SnO2 crystals with various morphologies were prepared by a facile hydrothermal method in the simple solution systems of SnCl2 and SnCl4, respectively. This process was carried out under mild conditions and required no high-temperature heat treatment. The morphological evolution with the preparation conditions was investigated. Various self-assembled hierarchical structures including microspheres assembled with nanoparticles, oriented nanocones, and flower-like, cabbage-like structures consisting of single-crystalline nanosheets were obtained by varying the solvent and the introduction of polyethylene glycol. A possible mechanism for the formation of the spherical hierarchically structures assembled by cone-like nanocrystals was proposed. (C) 2011 Elsevier B. V. All rights reserved.