This dissertation is devoted to physical properties research of piezoresistive polyisoprene nanographite composites (PNCC) and elaboration of entirely hyperelastic pressure sensor systhems (VSSS). Influence of various carbon allotropes and concentrations on composites piezoresistive sensitivity has been analyzed. Influence of various ultrasonic treatments on thermally exfoliated graphite particle sizes and piezoresistive behaviour in composites containing these fillers has been determined. PNCC piezoresistive sensitivity at various ambient temperatures and electrical resistivity changes with temperature has been determined. Quantitative analysis with literature proposed theoretical models has been made to explain PNCC resistivity dependance of temperature. A new theoretical model for electrically conducting polymer composites is proposed to explain positive temperature coefficient based on broadening of tunneling junctions and subsequent destruction of conducting channels due to composite matrix thermal expansion. Various sizes of VSSS has been elaborated from PNCC made in „Baltic Rubber Factory”. Influence of mechanical loading frequency on piezoresistive effect has been determined for PNCC composition used as VSSS sensitive element.