The synthesis, characterization and capacity studies of co-polymerized Al2O3 nanocomposites capable of adsorbing with Hg(II) ions are reported. Al2O3 nanoparticles was fabricated with combustion synthesis using inexpensive mixed fuels. Nanocomposite of poly (aniline-CO-O-anthranilic acid) (PANAA/ Al2O3) was synthesized by chemical oxidative polymerization of anthranilic acid and aniline co-monomers at equimolar ratios (1:1) with the Al2O3 nanostructure. The product was characterized by FT-IR, XRD, SEM and TEM techniques. The adsorption behaviors of the toxic Hg(II) were studied. The equilibrium isotherm, kinetics parameters and the thermodynamics investigations of the adsorption process were calculated. Thermodynamics investigations also confirmed that the adsorption capacity of Hg(II) on each adsorbent was spontaneous and exothermic.