An electric field-induced alignment characteristics of high structure carbon black (HSCB) nanoparticles in silicone oil base fluids with different viscosities were investigated in this work. Resistivity change versus time of HSCB/silicone oil fluids with different concentrations of HSCB filler at different electric field strengths from 10 to 250 V/cm. It was observed that the decrease of the electrical resistance versus time is steeper for larger electric field strengths and lower silicone oil viscosities. Measurement results were analyzed using percolation theory by calculating critical concentration at which rapid increase of conductivity appears. To evaluate the influence of the aligning electric field the possible lowest electric field strength (0.05 V/cm) was applied so the “zero field” percolation threshold was determined. The obtained results potentially can be used in the development of polymer composites with aligned nanoparticle structure. The financial support of Latvian National Research Program IMIS2 is greatly acknowledged.