This study investigated the adsorption of lead ions (Pb2+) by activated carbon modified with potassium permanganate (KMnO4). Activated carbon was chemically modified through impregnation with solutions of KMnO4 (0.01 mol/L and 0.03 mol/L). Adsorption experiments from aqueous solutions containing known amounts of Pb2+ were explored in a batch system. The amount of Pb2+ adsorbed at different pH values, initial concentrations, sorbent dosages, contact times, and temperature were determined by atomic absorption spectrometry (AAS) in order to determine the optimum conditions for Pb2+ adsorption. Moreover, the effects of common ions like sodium, potassium, calcium, and magnesium on the adsorption capacity were also studied. The Pb2+ adsorption on modified and unmodified activated carbon conformed to the Langmuir isothermal adsorption equation. Overall the modified activated carbon exhibited a higher adsorption capacity and stronger chemical affinity than pristine activated carbon. The rates of adsorption were found to conform to pseudo-second order kinetics.