Certain attention has been converted to polyisoprene-nanostructured carbon composites (PNCC) as prospective piezoresistive materials for use in pressure sensing applications or as a tactile element in robotics. Recent research approved that vulcanization process has an important role in process chain to obtain material with necessary mechano-electric properties. In current article we present an original attempt to investigate the development of percolative electroconductive structure of PNCC during vulcanization. The “in situ” measurements of electric conductivity have been performed to evaluate the change of materials electric resistivity directly during the vulcanization process. Samples with different vulcanization times have been evaluated using high frequency AC measurements as well as SEM analysis on fractured surfaces. The dependence of conductance G and capacitance Cp on AC frequency for PNCC samples with different vulcanization times confirmed the development of conductive grid during vulcanization process. The results have been presented and evaluated to make certain conclusions.