The present study aims to analyze the effects of Brownian motion and thermophoresis forces on the natural convection heat transfer of nanofluids around a vertical cone placed in a saturated porous medium. The range of non-dimensional parameters and the definition of two important parameters of heat and mass transfer are discussed. The results show that the range of Lewis number as well as Brownian motion and thermophoresis parameters and also the definition of the reduced Nusselt and Sherwood numbers, used in the previous analyses, should be reconsidered. In the present study, reasonable definitions of reduced Nusselt and Sherwood numbers have been proposed and discussed in details. In contrast with previous researches, the present results show that the heat transfer associated with migration of nanoparticles is negligible compared with heat conduction and convection mechanisms. (C) 2018 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.