Superstructures of BaCO3 microcrystals were prepared by using a thermal method from Ba(NO3)(2), N,N,N',N'-tetramethylethylenediamine (TMEDA), cetyltrimethylammonium bromide (CTAB), and glucose in an aqueous-cylcohexane bilayer system. The hierarchical self-assembled urchin-like BaCO3 superstructures form via the self-assembly of BaCO3 spindles. The choices of an aqueous-cyclohexane bilayer system and CTAB are important in the formation of the superstructures. The spindles are aligned toward the center of a sphere in spherical self-assemblies. The surfaces of these spherical BaCO3 products have an urchin-like morphology. HRTEM confirmed that the spindles grow along the crystallographic c-axis. (c) 2012 Elsevier Ltd. All rights reserved.