Antimony trioxide (Sb2O3) micro and nanostructures with various shapes have shown novel physical and chemical properties essential for technological applications. In the present study, we report the hydrothermal growth of a novel three-dimensional (3D) Sb2O3 grass-like microstructure by the direct reaction between SbCl3 and NaOH in a solution. The as-prepared 3D Sb2O3 microstructures consist of numerous microbelts with sharp tips and lengths of up to approximately 10 mu m, as well as widths of around 1.0 mu m. Other tunable architectures, including rose-like, cubic, belt-like, and bundle-like units, have also been prepared by changing the experimental conditions. The growth mechanism of Sb2O3 microstructures with grass shapes is speculated and analyzed in detail. Their optical properties are also surveyed using photoluminescence (PL) spectroscopy. A broad PL emission is revealed, suggesting potential applications in electronics and optoelectronics. Crown Copyright (C) 2011 Published by Elsevier B.V. All rights reserved.