The aim of this work is to investigate chemo-resistivity properties of natural rubber-carbon nanostructure composite, that’s why a change of diffusion characteristics and reversibility of electro-chemical properties of the composite with different degree values of crosslinks have been analysed. The composites are made from natural rubber (polyisoprene) as matrix material and high structure carbon black as electro-conductive filler. In order to investigate diffusion characteristics of volatile organic compounds (VOC) in relation to chemo-resistive response of composites simultaneous mass, length and electrical resistance change measurements of the samples, when samples are held in VOC and after exposures to VOC were carried out. Electrical resistance increase mechanism in the composite advances with the composite structure development during vulcanization.