Monodisperse hematite (alpha-Fe2O3) nanostructures with flower-like morphology were obtained by a simple forced hydrolysis and thermal decomposition method without the assistance of any template or organic surfactant. The microstructure of the final flower-like particles was characterized in detail by transmission electron microscopy and selected area electron diffraction, which showed the composite structure of the particle "core". Electron diffraction patterns obtained for sections located on the "leaf" of the particles were consistent with hematite single crystals, whereas those obtained for the middle of the particle showed additional spots, due to the presence of goethite in the particle core. Fourier transform infrared spectroscopy and X-ray diffraction also confirmed the presence of goethite phase in the particle. A mechanism based on nucleation-aggregation-recrystallization, which speculated that the goethite precipitates first and then hematite heterogeneously nucleates on goethite particles, was proposed. (C) 2008 Elsevier B.V. All rights reserved.