Metal ion contamination of drinking water and waste water, especially with heavy metal ion such as lead, is a serious and ongoing problem. In this work, activated carbon prepared from peanut shell (PAC) was used for the removal of Pb2+ from aqueous solution. The impacts of the Pb2+ adsorption capacities of the acid-modified carbons oxidized with HNO3 were also investigated. The surface functional groups of PAC were confirmed by Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), Boehm titration. The textural properties (surface area, total pore volume) were evaluated from the nitrogen adsorption isotherm at 77K. The experimental results presented indicated that the adsorption data fitted better with the Langmuir adsorption model. A comparative study with a commercial granular activated carbon (GAC) showed that PAC was 10.3 times more efficient compared to GAC based on Langmuir maximum adsorption capacity. Further analysis results by the Langmuir equation showed that HNO3 [20% (by mass)] modified PAC has larger adsorption capacity of Pb2+ from aqueous solution (as much as 35.5mg.g1). The adsorption capacity enhancement ascribed to pore widening, increased cation-exchange capacity by oxygen groups, and the promoted hydrophilicity of the carbon surface.