A central composite design (CCD) was employed to optimize the biosorption of Pb(II) ions onto immobilized cells of Pycnoporus songuineus. The independent variables were initial Pb(II) concentration, pH and biomass loading. The combined effects of these variables were analyzed by response surface methodology (RSM) using quadratic model for predicting the optimum point. Under these conditions the model predicted a maximum of 97.7% of Pb(II) ions removal at pH 4, 200 mg/L of initial Pb(II) concentration with 10 g/L of biosorbent. The experimental values are in good agreement with predicted values within +0.10 to +0.81% error. Crown Copyright (C) 2008 Published by Elsevier Ltd. All rights reserved.