Homogeneous CuO/SiO2 and NiO/SiO2 nanocomposite coatings containing CuO and NiO nanoparticles in silica matrix were successfully synthesized by sol-gel process on an aluminum alloy substrate, respectively. The evolution of phase and morphology of both nanocomposites was characterized by XRD, SEM, TEM and FTIR. The effect of incorporating various nanoparticles on the corrosion behavior and the thermal conductivity of nanocomposite coatings was investigated by potentiodynamic polarization curve and comparative exponential method. The thermal conductivity as well as the corrosion resistance of nanocomposite coatings was significantly improved by the introduction of metal oxide particles. In comparison with NiO/SiO2 nanocomposite coatings, CuO/SiO2 composite coatings displayed lower protective behavior as well as higher thermal conductivity. Experimental results revealed that those improvements can directly be related to the nanocomposite effect and the nature of added nanoparticles. (C) 2008 Elsevier B.V. All rights reserved.