Effects of operating parameters such as pH, temperature, Cu(II) ion and the adsorbent concentrations and particle size on batch biosorption kinetics of copper(II) ions onto pre-treated powdered waste sludge (PWS) were investigated. Pseudo-first and second order kinetics were used for correlation of pre-equilibrium biosorption data and the rate constants were determined. The pseudo-second order kinetics was found to be more suitable for representation of the kinetic data for almost all cases. Kinetic constants increased with increasing pH, temperature and PWS concentration, but decreased with increasing Cu(II) concentrations and the particle size of PWS. The highest rate constants for the pseudo-first and second order kinetics were 0.808 h(-1) and 0.0309 (mg/g)(-1) h(-1), respectively for the smallest particle size of 53 mu m. The highest Cu(II) biosorption capacity of 156 mg g(-1) was obtained with PWS and Cu(II) concentrations of 0.25 g l(-1) and 100 mg l(-1) with the smallest particle size (D-p < 53 mu m). (C) 2007 Elsevier Inc. All rights reserved.