The synthesis of calcium carbonate (CaCO3) crystals from aqueous solutions containing anion surfactants (sodium dodecylsulfonate (DDS), sodium dodecylbenzenesulfonate (SDBS)) or anionic surfactant-poly(N-vinyt-1-pyrrolidone) (PVP) complexes has been performed by the method of rapid mixing of the solutions of calcium chloride (CaCl2) and sodium carbonate (Na2CO3 followed by 10-h incubation under stirring. Polymorphism. of CaCO3 crystals was observed in different additive systems. In pure anionic surfactant systems, DDS induced the transformation of initially formed amorphous CaCO3 to calcite, while SDBS favored the formation of vaterite as the final product. The addition of PVP into the above two anionic surfactant systems, promoting the formation of supermolecular complexes of surfactant/polymer, resulted in a distinct variation of the morphology of CaCO3 crystals. The polymorphs of CaCO3 are dependent not only on PVP but also on DDS or SDBS concentrations in the complex solution, i.e., anionic surfactants control the crystalline phase, but PVP only changes the crystal shape. (C) 2004 Elsevier B.V. All rights reserved.