In this research, graphene nanosheets were covalently functionalized with different amines and characterized by several techniques and their thermal and electrical properties were investigated. Then, functionalized graphenes were used as filler in the polymeric nanocomposite (NC) synthesis. At the first, the graphene functionalized by tris(hydroxymethyl)aminomethen and poly(vinyl alcohol) (PVA) was used a a polymer matrix. PVA and functionalized grapheme oxide (FGO) NC films prepared through a simple - solution casting method. The fabricated NCs were investigated and studied by different analytical methods like FT-IR, XRD, TGA, FE-SEM and TEM. The mechanical properties of the NC membranes were also studied. Thermal stability and mechanical resistance of the NCs were improved due to high dispersion of nanofiller in the polymer matrix and the existence of hydrogen bonding interaction between functional groups on the filler and polymer OH groups. The oxygen permeability of the NCs was examined which increased remarkably by adding nanofiller due to an increase in hydrophilic volume. In the second part, the effect of glutaraldehyde (GA) as a crosslinking agent on the mechanical, thermal and chemical properties of PVA NCs was investigated. The NC films were formed by reaction between hydroxyl groups of PVA and tris(hydroxymethyl)aminomethen functionalized graphene with GA results a crosslinked network structure. In the next project, biosafe and environmentally friendly amino acid was chosen to modify the graphene surface. The functionalization was achieved by reacting the -NH 2 groups of L-histidine with the oxygenated functional groups (epoxide and carboxylate groups) of GO sheets by a simple and green procedure. Then, hydrazine monohydrate was chosen as a reducing agent to obtain R-FGO. The resultant functionalized graphene was characterized with various techniques and its thermal and electrical properties were examined. In the next step, the poly(ether sulfone) was used as matrix and new series of NCs were fabricated using reduced L-histidine functionalized graphene (R-FGO) as nanofiller through solution mixing method. For preparation of polymeric NCs, poly(ether sulfone) (PES) was sulfonated and was characterized by FT-IR, CHNS and 1 H-NMR techniques. The fabricated NCs were investigated and studied by different analytical methods like FT-IR, XRD, TGA, FE-SEM and TEM. Finally, proton conductivity of sulfonated PES and its NCs was examined and the results show that proton conductivity increased by increasing R-FGO content.