Calcium carbonate (CaCO3) was crystallized in (2-hydroxypropyl-3-butoxy) propyl-succinyl chitosan (HBP-SCCHS) solutions by a slow vapor diffusion method. The CaCO3 crystals were characterized by scanning electron microscopy (SEM), powder X-ray diffraction (XRD), Fourier transform infrared (FIR) spectroscopy, thermogravimetry analysis (TGA) and N-2 adsorption-desorption methods. By varying the concentrations of HBP-SCCHS and Ca2+, temperature and initial pH, the CaCO3 crystals with different morphologies were obtained. Based on the analysis of CaCO3 crystals obtained under different conditions, the mechanisms of the CaCO3 crystallization in the presence of HBP-SCCHS were proposed. It was found that the adsorption of HBP-SCCHS molecules on CaCO3 surfaces played a key role in the formation of CaCO3. (C) 2011 Elsevier B.V. All rights reserved.