Ion implantation is a surface treatment process in which the surface of a sample is bombarded with a beam of energetic dopant ions to implant ions into the matrix of the substrate. In the present work, nanocomposites of poly(3,4-ethylenedioxy thiophene) /poly(4-styrene sulphonate) (PEDOT: PSS) and nanographite are prepared and subjected to swift heavy ion implantation using the same ion as that of the filler in the nanocomposites. PEDOT: PSS/ nanographite nanocomposites have been synthesized by solution blending method. The prepared PEDOT: PSS/ nanographite nanocomposite films were irradiated with carbon ions (C ion beam, 50 MeV) in fluence range of 3 × 10 10 to 3 × 10 12 ions/cm 2 . The nanocomposite films were characterized by scanning electron microscope (SEM) and X-ray diffraction (XRD) before and after C ion implantation and were evaluated for their electrical and sensor properties. SEM and XRD studies clearly depict the homogeneous dispersion of nanograhite in polymer matrix along with densification of the polymer nanocomposite. The implanted nanocomposites exhibit better electrical and sensor properties for the detection of nitroaromatics.