A new numerical model taking into account the random dispersion of nanofillers in a polymer matrix has been developed in order to predict the electrical percolation behavior of bulk and porous media incorporating 1D- carbon nanotubes (CNTs) and/or 2D- graphene nanoplatelets (GNPs). The numerical model uses applied vector calculus and linear algebra, and is able to predict the electrical percolation threshold of bulk systems assuming a perfect random dispersion and orientation of the nanofillers, resulting in a percolation volume of 0.023 and 1.628 vol% for CNTs and GNPs nanocomposites, respectively, showing a quantitative agreement with existing experimental observations [1]. CNTs were more efficient in forming a percolative network than GNPs, especially when using high aspect ratio fillers.The percolation volume was found to decrease with the aspect ratio of CNT and GNP according to different relationships, while hybrid systems incorporating CNTs and GNPs exhibited significant synergistic effects when the two fillers were properly combined. The numerical model is also able to predict the percolation threshold in the case of porous morphology, showing a decrease in percolating volume with porosity due to filler confinement within the pore walls [2]. The parametric study of the present model can shed some light on how one can maximize the benefits arising from using different conductive fillers and tailor the polymer foam morphology to minimize the percolation threshold. Keywords: Carbon nanotubes; Graphene; Hybrid Systems; Numerical modelling; Porous materials; [1] Yue L, Pircheraghi G, Monemian SA, Manas-Zloczower I. Epoxy composites with carbon nanotubes and graphene nanoplatelets – Dispersion and synergy effects. Carbon 2014;78:268-78. [2] Ameli A, Nofar M, Park CB, Pötschke P, Rizvi G. Polypropylene/carbon nanotube nano/microcellular structures with high dielectric permittivity, low dielectric loss, and low percolation threshold. Carbon 2014;71:206-17.