The combination of high electrical conductivity and high aspect ratio of the carbon nanotubes (CNT) made these nanoparticles highly attractive for use as conductive additives in insulating polymeric matrices. Usually very low CNT concentration is necessary to achieve a nanocomposite with electrical conductivity high enough for use in electrostatic dissipation applications or electromagnetic interference (EMI) shielding. The minimum concentration of CNT to obtain good conductivity depends on the formation of CNT networks paths in the polymer matrix and therefore variables that affect the dispersion of CNT on polymer matrix can have significant influence on the electric percolation threshold. In this work, epoxy/CNT nanocomposites were produced using a high energy sonication process and the effect of the addition of solvent and mineral fillers on the nanocomposites conductivity and morphology were evaluated. The nanocomposites prepared by adding solvent during their preparation promoted a decrease of the percolation threshold from 0.08 wt% to 0.05 wt% and one order of magnitude increase in the electric conductivity for a 0.1wt% CNT concentration. This attractive improvement was correlate with the increase of the agglomeration of CNT observed on a micro-scale due to the higher mobility of the CNT in the low viscosity mixture epoxy/solvent. The incorporation of the mineral filler calcium carbonate promoted just small increments on the electric conductivity when added in the epoxy resin, but a synergic effect was observed when this mineral filler was added in the mixture epoxy/solvent, and an electrical conductivity of 1.28  10-3 S/m was reached for a nanocomposite with only 0.1wt% of CNT.