A series of poly(ethylenimines) (PEI) coated onto silica gels has been tested for the ability to complex lead and mercury in aqueous solutions. The study of the kinetics of metal uptake revealed that all sorbents exhibit a fast rate of sorption. The saturation capacities of the different systems were evaluated according to the Langmuir equation. The influence of different parameters like pH, textural characteristics of silica, and amount of coated polymer were discussed. Finally, cycles of stripping and sorption for lead metal were investigated in column system to evaluate the long-term stability of the sorption properties. One striking result was that crosslinking PEI onto silica prevents the desorption of PEI and greatly improves the sorption capacity.