The present study shows that NiO-nanoparticles prepared by the organic solvent method is more active than that prepared by the precipitation method for removal of Pb(II) ions from aqueous solutions. The adsorption process is a function of the adsorbent and adsorbate concentrations and contact time. Equilibrium was achieved practically in 2 h. Langmuir model is found to be in a good agreement with experimental data on adaptive behavior of Pb(II) ions on NiO. Nickel oxide is then considered as a useful catalyst for the treatment of wastewater containing lead.