At first, Ca/Fe layered double hydroxides (LDHs) with intercalate anions of citrate and tartrate were prepared, and then 3-aminopropyl triethoxysilane (KH550) coupling agents were used to modify the LDH surfaces. Then, in order to improve the thermal stability and increased efficiency in removal of heavy metals, polymer nanocomposites were prepared by in situ polymerization of polyaniline (PANI) in the presence of modified LDH nanoparticles. The synthesized nanocomposites (NCs) were characterized by various techniques including FT-IR and X-ray diffraction )XRD( and their morphology was investigated by field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). Morphological studies revealed that modified LDH were dispersed in polymer matrix without any aggregation. The TGA of the obtained NCs showed that LDH / PANI nanocomposites have a higher thermal stability than ure polyaniline. In the final part of the project, polyaniline and synthesized NCs were used as adsorbents to removal of (II) from aqueous solution. Then parameters including pH, contact time and initial concentration of salt were optimaized. Also, the sorption kinetics and isotherm of these sorbents were investigated. The results showed that the kinetic adsorption could be described by a pseudo- first order model very well for the removal of lead ion (II). Comparing the results of Langmuir and Freundlich equations showed that NC (10%) with more adsorption capacity (q max ) and adsorption constant (K l ) were more suitable adsorbent tha NC (5%) and PANI for removal Pb (II). According to the relevant R 2 s, the Langmuir model showed the best fit on the lead absorption data by PANI and the synthesized Cit-LDH / PANI NCs.