A novel biomimetic method is described for the mineralization of CO32- ions of water as CaCO3 in each gelatinous matrix of chitin and chitosan using CaCl2 as a water-soluble CO32- ions. Each gelatinous CaCl2-composite (40-87% CaCl2) of chitin and chitosan was prepared by two method: 1) the entrapping of CaCl2 into each gelatinous granule of chitosan and chitin, and 2) the soaking of each gelatinous granule or square slice of chitosan and chitin in aqueous CaCl2 solutions. The gelatinous composite was soaked in aqueous 1M K2CO3 solution at room temperature to give the corresponding white CaCO3-composite (17-30% CaCO3). In these products, CO32- ions were detected by FT-IR absorptions at 1425, 876 and 712 cm(-1).