The biosorption behaviors of antimony(III) by cyanobacteria Microcystis were investigated under various environmental parameters to evaluate the potential of Microcystis to remove Sb(III). The maximum biosorption capacity was determined to be 4.88 mg/g (dry weight) at pH 4.0. The biosorption process followed the pseudo-second-order rate kinetics. There were increasingly inhibitive effects of ionic strength of NaCl on the biosorption capacities. The high desorption efficiency was achieved using 4 mol/L HCl. The regeneration studies show that the biomass could be used for a minimum of five repetitive cycles. The ATR-IR spectra analysis suggested the involvement of carboxyl, hydroxyl and amino groups in Sb(III) biosorption through surface complexation. Furthermore, the results of speciation analysis found the concurrence of oxidation of Sb(III) with the biosorption process, which is beneficial to alleviate the ecological toxicity of Sb(III). The chemical conversion of Sb(III) into Sb(V) was pH and time dependent. The results are of significance to the further understanding of the biosorption of Microcystis to remove toxic metals. (C) 2011 Elsevier B.V. All rights reserved.