With the rapid industrial and economic growth, various pollutants particularly heavy metals, have entered the environment. Lead (Pb) is one of the most toxic and most common heavy metals in aquatic ecosystems and water resources. Various processes have been developed to remove Pb and other metals from aqueous solutions among which sorption processes is particularly important due to its high efficiency, ease of use, and low costs. Polymeric sorbent have great capacity to remove heavy metals from polluted waters but these sorbents have low physical and structural stabilities. To improve the physical and chemical properties of polymeric sorbents and to increase their sorption capacity, mineral nanoparticles, such as layered silicates, are added to the polymer matrix to develop polymer nanocomposites. Moreover, to enhance the catalytic properties and sorption properties of the silicate clays, these mineral nanoparticles are modified using organic compounds, such as amino acids, before being added to the polymer matrix. In this study, poly (vinyl alcohol)/alginate composites were synthesized in the presence of bentonite and bentonite modified with cysteine. The synthesized composites were characterized using XRF, XRD, FT-IR, SEM and TEM methods. Results showed that cysteine was penetrated into the interlayer space of bentonite. Also, the results confirmed that a bentonite/poly (vinyl alcohol)/alginate and a cysteine-bentonite/poly (vinyl alcohol)/alginate nanocomposites have been synthesized with a mixture of intercalated and exfoliated microstructures. Lead sorption isothermal behavior of the composites were studied as a function of initial Pb concentration, pH and contact time. Freundlich, Langmuir, Koble-Currigan, Temkin, and Dubinin-Radushkevich isotherm models were fitted to the Pb sorption data. Based on the results, all isothermal models have good fits to the Pb sorption data. However, the Langmuir model was superior in describing the data. The maximum sorption capacity predicted from the Langmuir model for poly (vinyl alcohol)/alginate composites in the presence and absence of bentonite and cysteine-bentonite was 0.480, 0.724 and 0.955 mmol g -1 , respectively. Effect of pH on sorption properties of the composites was also determined in the pH range of 2 to 9. The maximum Pb sorption capacity occurred for all three sorbents at pH=5. Kinetic studies of Pb sorption on the composites at constant Pb concentration and pH value were also performed during 9 hours. Pseudo-first-order, pseudo-second-order, Elovich, Parabolic diffusion, and Power function models were used to describe the kinetic data. According to the results, the time of reaching the equilibrium was estimated to be 4-5 hours. All kinetic models were able to describe the Pb sorption data by all the three sorbents; however, the Elovich model was superior . It can be concluded that with the addition of bentonite, and in particular cysteine-modified bentonite, to poly (vinyl alcohol)/alginate composite, the capacity and rate of Pb sorption significantly increases. The nanocomposites synthesized in this study are suitable candidate sorbents for removal of Pb from aqueous solutions. Keywords : anocomposite, Poly (vinyl alcohol), Alginate, Bentonite, Cysteine, Lead, Adsorption