Calcium carbonate (CaCO3) crystals with various shapes have been synthesized by aging calcium chloride and urea hybrid solution containing sodium dodecylsulfonate (SDSN) or sodium dodecylbenzenesulfonate (SDBS) in a 90 degrees C bath. The effects of SDSN and SDBS on the morphology and polymorph of precipitated CaCO3 are investigated with the help of scanning electron microscopy (SEM), Fourier transform infrared (Fr-IR) spectrometer and X-ray diffraction (XRD). Flower-like vaterite changes from monolayer to multilayer structure with the increase of SDSN concentration. While the crystal shape changes from plate-like, through rose-shaped, hat-like, to bicone-like as the concentration of SDBS is increased. (c) 2007 Elsevier Ltd. All rights reserved.