Research in thermal conductivity of nanofluids started only over the past decades. A great number of numerical and theoretical models have been proposed by several authors to predict the anomalous high thermal conductivity at hus, the total heat flux olow nanoparticles concentrations. This paper presents a new correlation of Nusselt number developed from the experimental data of nanofluids. Than a thermal conductivity model of nanofluids has been derived, based on the Monte Carlo simulations combined with the new Nusselt number correlations. The present work predicts the thermal conductivity of several nanofluids Al2O3/H2O, CuO/H2O, TiO2/H2O and CNT/H2O with a good accuracy. In addition this model takes into account nanofluid temperature variation and different nanoparticles size. Moreover the results of the present model are shown in good agreement with the existing experimental data. (C) 2014 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.