Nowadays, developing a simple, efficient, and low-cost route for synthesizing three-dimensional (3D) micro/nanostructures has become the research focus of nanomaterials. In this work, 3D SnO2 microstructures assembled by nanosheets were prepared by hydrothermal synthesis combined with subsequent heat treatment. The morphology and crystal structure of the SnO2 were characterized by X-ray diffraction, field emission scanning electron microscope, transmission electron microscope and N-2 adsorption-desorption isotherms. The as-prepared tin oxide samples show 3D hierarchical structures assembled with two-dimensional nanosheets. After sintering at 500 degrees C, the sample has better crystallinity of SnO2 with a larger specific surface area of 62.5 m(2)/g than that (24.1 m(2)/g) of commercial SnO2 materials. The 3D SnO2 microstructures have been studied for ethanol gas sensing, showing good response-recovery performance, high sensitivity and excellent long-term stability and repeatability even after 4 months. The results demonstrate that 3D SnO2 microstructures are promising for application as a gas sensor material. (C) 2013 Elsevier B.V. All rights reserved.