The sorption of Hg(II) from aqueous solution onto the dead biomass of the aquaphyte Potamogeton natans was studied. The uptake was studied by placing the Hg(II) solutions into beakers containing various concentrations of biomass. Factors influencing the sorption process such as reaction time, initial pH value of the treated solution, and initial concentration of metal ions were examined. Chemical and instrumental analyses including atomic absorption, electron microscopy and X-ray energy dispersion analyses were used to elucidate sorption mechanisms. It was found that, although sorption of Hg(II) took place aver the entire biomass surface, there were spots on the surface where apparent multilayer sorption of Hg(II) occurred. The maximum uptake of Hg(II) by P. natans biomass is about 180 mg/g biomass. The minimum concentration of Hg(II) in solution that can be achieved appears to be limited to about 4-5 mg/l. (C) 2002 Published by Elsevier Science Ltd.