Effect of 100 MeV swift heavy ions [silver ( Ag 8 + ) ] on morphological and electrical properties of polypyrroleHigh energy ͑MeV͒ C 2+ , F 2+ , and Cl 2+ ions were irradiated onto -conjugated polyaniline emeraldine base (PAN-EB) samples. The energy of an ion beam was controlled to a range of 3 -4.5 MeV, with the ion dosage varying from 1 ϫ 10 12 to 1 ϫ 10 16 ions/ cm 2 . The highest dc conductivity ͑ dc ͒ at room temperature was measured to be ϳ60 S / cm for 4.5 MeV Cl 2+ ion-irradiated PAN-EB samples with a dose of 1 ϫ 10 16 ions/ cm 2 . We observed the transition of high energy ion-irradiated PAN-EB samples from insulating state to conducting state as a function of ion dosage based on dc and its temperature dependence. The characteristic peaks of the Raman spectrum of the PAN-EB samples were reduced, while the D-peak (disordered peak) and the G peak (graphitic peak) appeared as the ion dose increased. From the analysis of the D and G peaks of the Raman spectra of the systems compared to multiwalled carbon nanotubes, ion-irradiated graphites, and annealed carbon films, the number of the clusters of hexagon rings with conducting sp 2 -bonded carbons increased with ion dosage. We also observed the increase in the size of the nanocrystalline graphitic domain of the systems with increasing ion dosage. The intensity of normalized electron paramagnelic resonance signal also increased in correlation with ion dose. The results of this study demonstrate that -conjugated pristine PAN-EB systems changed from insulating state to carbonized conducting state through high energy ion irradiation with high ion dosage.