The biosorption of cadmium and lead ions from artificial aqueous solutions using waste baker's yeast biomass was investigated. The yeast cells were treated with caustic, ethanol and heat for increasing their biosorption capacity and the highest metal uptake values (15.63 and 17.49 mg g(-1) for Cd2+ and Pb2+, respectively) were obtained by ethanol treated yeast cells. The effect of initial metal concentration and pH on biosorption by ethanol treated yeast was studied. The Langmuir model and Freundlich equation were applied to the experimental data and the Langmuir model was found to be in better correlation with the experimental data. The maximum metal uptake values (q(max) mg g(-1)) were found as 31.75 and 60.24 for Cd2+ and Pb2+, respectively. Competitive biosorption experiments were performed with Cd2+ and Pb2+ together with Cu2+ and the competitive biosorption capacities of the yeast biomass for all metal ions were found to be lower than in non-competitive conditions. (C) 2004 Elsevier Ltd. All rights reserved.