Adsorption of lead(II) ions onto activated carbon prepared from renewable plant material, which is Euphorbia rigida, was investigated with the variation in the parameters of pH, contact time, the amounts of adsorbent, lead(II) ions concentration and temperature. Adsorption data of lead(II) ions onto activated carbon by E. rigida obeys the Langmuir isotherm model. Maximum adsorption capacity (q(max)) of lead(II) ions onto adsorbent was 1.35 x 10(-3) mol g(-1) or 279.72 mg g(-1) at 40 degrees C. Three kinetic models are the first-order, pseudo- second-order and intraparticle diffusion equations. were selected to interpret the adsorption data. Kinetic parameters such as the rate constants, equilibrium adsorption capacities and related correlation coefficients, for each kinetic model were calculated and discussed. It was indicated that the adsorption of lead(II) ions onto activated carbon by E. rigida could be described by the pseudo-second-order kinetic model and also followed the simple external diffusion model the initial 10 min and then by intraparticle diffusion model up to 50 min. (c) 2007 Elsevier B.V All rights reserved.