The effect of mixed filler system consisting of carbon black (CB) and multi-wall carbon nanotubes (MWCNTs) on electrical properties and molecular rheology of melt compounded injection molded composites with polycarbonate (PC) was investigated. Pure CB or MWCNTs or mixtures of CB and MWCNTs in mass ratio 50/50 were added to PC using injection molding process to prepare the samples with filler concentrations between 0.5, 1 and 2 wt %. SEM observations on thin sections demonstrated a suitable distribution of fairly small CB aggregates and good dispersion of the MWCNTs in nanocomposites. Composites with pure MWCNTs were shown a lower electrical percolation and higher melt viscosity due to the nature of these nano-materials. Because the samples did not show a lower electrical percolation than calculated from the values of pure nano fillers in PC, no synergistic effect between CB and MTWNTs could be found in the samples. Linear rheological investigations were done on the samples and it was observed that rheological properties were more influenced by MWCNTs than CB. Linear rheological measurements at low frequencies were shown than Carbon black aggregates influenced the structure of MWCNTs in the system, which may influence the electrical and reversibility of the MWCNTs orientations too. Because the changes and reversibility in the MWCNTs states are very critical in the electrical applications, the effect of CB in the systems must be investigate. In order to find the effect of CB on reversibility of the MWCNTs orientations in the process non-linear rheological measurements were done on the nanocomposites. It was also observed that these hybrid nanocomposites showed suitable electrical properties compared to the pure ones and this has a economical advantage of using less amounts of MWCNTs.