||This study described the characterization of polymer composites, where the single-walled carbon nanotube (SWNT) and carbon black (CB) were incorporated into polypropylene (PP) in order to evaluate the potential synergistic effects on the interaction of these two electrical conductive fillers. The composites were prepared by melt processing with co-rotating twin-screw extruder equipped with the back-conveying element and controlled residence time of 20 min. In our previous study, only SWNT was introduced into PP composites, and it was found that electrical percolation threshold was 1.4 wt.% with approximately 10 S/m of volume conductivity. Thus, the composites of this study were produced with varying ratio of SWNT and CB at 1.4 fixed weight percent if these two electrical conductive fillers improve that electrical volume conductivity. A higher volume conductivity was found from the SWNT:CB ratio of 7:3 than the composites containing SWNT only.