Hollow microsphere assembled by a number of tin oxide nano-sheets was prepared with a simple hydrothermal approach, and its phase transitions was observed by an annealing treatment which shows that the un-annealed samples are dominated by SnO with minor impurities of Sn3O4 and SnO2. With the increase of the annealing temperature, both SnO and the impurity Sn3O4 transfer to SnO2 starting at annealing temperature 420 degrees C as observed from the Raman spectroscopy measurements. We found that the annealing temperature has no effects on the morphologies of the hollow microsphere, and the near band gaps are equal to 2.8, 2.1-2.3 and 3.4-3.6 eV, for SnO, Sn3O4 and SnO2, respectively. Besides these, our photoluminescence spectrum measurements exhibit several emissions with the wavelength ranging from 420 to 530 nm for all samples, while for samples annealed at 700 degrees C there are additional two peaks appearing at the wavelength 377.5 and 399 nm. (C) 2015 Elsevier Ltd. All rights reserved.