In this study, activated carbon was prepared from pumpkin seed shells by ZnCl2 (chemical) activation at an impregnation ratio of 3/1 and a carbonization temperature of 500 degrees C. The prepared activated carbon was used to remove lead(II) ions from aqueous solutions. The BET surface area and micropore volume of the obtained activated carbon was 1564 m(2)/g and 0.526 cm(3)/g, respectively. Optimum adsorption conditions were determined as a function of initial pH, contact time, temperature, adsorbent dosage and initial lead(II) concentration. Langmuir isotherm provided the best fit to the equilibrium data with maximum adsorption capacity of 36.33 mg/g. The kinetic data were found to follow closely the pseudo-second-order model. The thermodynamic parameters such as AG, AH and AS were calculated for predicting the nature of adsorption.