MnCO3 with hierarchical superstructures such as chrysanthemum, straw-bundle, dumbbell and sphere-like were synthesized in water/ethanol system under environment-friendly hydrothermal condition. In the synthesis process, the CO2 in atmosphere was used as the source of carbonate ions and Schiff base was used as shape guiding-agent. The different superstructures of MnCO3 could be obtained by controlling the hydrothermal temperature, the molar ratio of manganous ions to the Schiff base, or the volume ratio of Water to ethanol. A tentative growth mechanism for the generation of MnCO3 superstructures was proposed based on the rod-dumbbell-sphere model. Furthermore, the MnCO3 as precursor could be further successfully transferred to Mn2O3 microstructure after heating in the atmosphere at 500 degrees C, and the morphology of the Mn2O3 was directly determined by that of the MnCO3 precursor. (C) 2011 Elsevier Ltd. All rights reserved.