In the present study, the mesoporous structure of silica (mSiO(2)) nanoparticles as well as hemiaminal grafted mSiO(2) decorated by metallic silver (Ag/mSiO(2)) has been used for the preparation of glycerol based nanofluids. Structural and morphological characterization of the synthesized products have been carried out using Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), X-ray diffraction (XRD), UV-vis spectroscopy, inductively coupled plasma (ICP) and N-2 adsorption-desorption isotherms. The thermal conductivity and viscosity of the nanofluids have been measured as a function of temperature for various weight fractions and silver concentrations of mSiO(2) and Ag/mSiO(2) nanoparticles, respectively. The results show that the thermal conductivity of the nanofluids increase up to 9.24% as the weight fraction of mSiO(2) increases up to 4 wt%. Also, increasing the percent of the silver decorated mSiO(2) (Ag/mSiO(2)) up to 2.98% caused an enhancement in the thermal conductivity of the base fluid up to 10.95%. Furthermore, the results show that the nanofluids have Newtonian behavior in the tested temperature range for various concentrations of nanoparticles. (c) 2013 Elsevier Ltd. All rights reserved.