Two types of commercial multiwall carbon nanotubes (MWCNTs), Baytubes (R) C70P and C150P were incorporated into polypropylene (PP) using melt blending technique that employs a twin screw extruder (TSE) to prepare the nanocomposites of two different concentrations (1 and 3 wt%). Subsequently, American Society for Testing and Materials (ASTM) standard samples were prepared with an injection molding machine. The prepared nanocomposites were characterized by their rheological and electrical properties using a rheometer and a picoammeter/voltage source, respectively. The effect of different types of MWCNTs and loading percentage in rheological and electrical properties was investigated in detail. The rheological analysis demonstrated a considerable dependence of the melt rheological properties of the PP/MWCNTs nanocomposites on the MWCNTs loading. The storage modulus (G '), loss modulus (G '') and complex viscosity |eta*| increased with increasing MWCNTs loading. In addition, type C70P exhibited superior rheological properties compared to C150P. In terms of electrical properties, the addition of MWCNTs in the PP matrix decreased the volume resistivity of the matrix in a manner, proportional to the MWCNTs loading. No significant difference in volume resistivity was observed between the MWCNTs types. POLYM. ENG. SCI., 54:1134-1143, 2014. (c) 2013 Society of Plastics Engineers