Biosorption of lead (II) onto the biosorbent, represented by untreated S. cerevisiae and NaOH-treated S. cerevisiae was examined and the effects of contact time were investigated. The lead (II) biosorption was fast and equilibrium was attained within 90 mins. The maximum removal ratios of lead (II) for untreated S. cerevisiae and NaOH-treated S. cerevisiae after 3 h were 48.6% and 92.5%, respectively, with initial lead (II) concentration of 40 mg/L and optimum pH of 5.0. Data obtained from batch studies fitted well with the Langmuir isotherm model. Maximum adsorption capacity of lead (II) onto NaOH-treated S. cerevisiae was 21.6 mg/g at biosorbent dosage of 2 g/L at 25 °C. The nature of functional groups (i.e. amino, carboxyl and hydroxyl) and metalion interactions was examined by the FT-IR technique.