Posidonia oceanica leaves have been pre-treated with HCl solutions to elaborate a biosorbent that was carried out for Pb(II) sorption at pH 4 and pH 5. The sorption of Pb(II) was characterized using SEM-EDAX, XPS spectrometry and FT-IR spectroscopy. Maximum sorption capacity reached up to 140 mg Pb g(-1) at pH 5. The uptake kinetics were controlled by chemisorption reaction rate. This was correlated to the lamellar structure observed using SEM analysis. The influence of sorbent dosage, particle size and metal concentration on uptake kinetics was also investigated. Sorption performances are compared to other biosorbents and to previous studies on P. oceanica for binding of mineral and organic compounds. (C) 2011 Elsevier B.V. All rights reserved.