The biosorption of zinc ions from aqueous solution by Syzygium cumini L. was studied in a batch adsorption system as a function of pH, contact time. zinc ion concentration, adsorbent dosage and adsorbent size. The biosorption capacities and rates of zinc ions onto S. cumini L. were evaluated. The Langmuir and Freundlich adsorption models were applied to describe the isotherms and isotherm constants. Biosorption isothermal data could be well interpreted by the Langmuir model followed by Freundlich model with maximum adsorption capacity of 35.84 mg/g of zinc ion on S. cumini L. leaves biomass. The kinetic experimental data was properly correlated with the second-order kinetic model. (C) 2008 Elsevier B.V. All rights reserved.