Chitosan-coated calcium silicate hydrate (CSH/chitosan) mesoporous microspheres formed by self-assembly of nanosheets have been synthesized in aqueous solution under ambient conditions without using any toxic surfactant or organic solvent. The method reported herein has advantages of simplicity, low cost and being environmentally friendly. The BET specific surface area of CSH/chitosan mesoporous microspheres is measured to be as high as similar to 356 m(2) g(-1), which is considerably high among calcium silicate materials. The as-prepared CSH/chitosan mesoporous microspheres are promising adsorbent and exhibit a quick and highly efficient adsorption behavior toward heavy metal ions of Ni2+, Zn2+, Cr3+, Pb2+ Cu2+ and Cd2+ in aqueous solution. The adsorption kinetics can be well fitted by the pseudo second-order model. The maximum adsorption amounts of Ni2+, Zn2+, Pb2+, Cu2+ and Cd2+ on CSH/chitosan mesoporous microspheres are extremely high, which are 406.6, 400, 796,425 and 578 mg/g, respectively. The CSH/chitosan adsorbent exhibits the highest affinity for Pb2+ ions among five heavy metal ions. The adsorption capacities of the CSH/chitosan adsorbent toward heavy metal ions are relatively high compared with those reported in the literature. (C) 2013 Elsevier Inc. All rights reserved.