Immiscible polymer blends based on high-impact polystyrene/ethylene vinyl acetate (HIPS/EVA) are interesting host multiphase systems for the incorporation of low concentrations of carbon black (CB). The conductive filler CB tends to accumulate preferentially within the EVA phase, forming segregated structures, and thus conductivity of the blends is only obtained when double percolation is realized. Material properties such as surface tension and crystallinity of the CB-containing polymer are found to influence filler distribution, accordingly affecting the electrical conductivity. A rheological-electrical method is presented, whereupon extrudates of CB-containing binary immiscible polymer blends are produced by a capillary rheometer, and the effect of shear level on the extrudates＇ structure and resultant resistivity is determined. A descriptive model was derived, illustrating the effect of shear on double percolation at various blend compositions. The flow behavior of the CB-containing compounds was studied in regard to the filler packing factor, phi(m), and related to the electrical properties of the extrudates. Blend composition, CB content, and shear level were considered as significant parameters, determining the structure and the resultant electrical properties.