This paper presents a biosorption procedure for the preconcentration of Pb(2+) ions using Saccharomyces cerevisiae biomass. The influence of several factors including pH, biomass dosage, contact time, and temperature on biosorption efficiency were optimized. At optimum value of all the equilibrium, thermodynamic, and kinetic parameters of Pb(2+) ion biosorption was investigated by testing the Langmuir and Freundlich models and first and second order kinetic models were applied. The biosorption capacity of S. cerevisiae biomass was determined 89.6 mg/g, while the retained Pb(2+) ions by S. cerevisiae were reversibly eluted using 5 mol/L HNO(3). Due to the high stability of S. cerevisiae the applied biomass can be used successively ten times with a slightly decrease (about 20%) in the recovery of Pb(2+) ions. The calculated thermodynamic parameters, Delta G degrees, Delta H degrees, and Delta S degrees showed that the biosorption of Pb(2+) ion onto S. cerevisiae biomass was feasible, spontaneous, and endothermic under examined conditions. The results of kinetic analysis showed that the biosorption processes of Pb(2+) ions onto S. cerevisiae biomass followed pseudo second order kinetics.