Polymers owe many of their properties due to their long chain molecular structure and have opened many vistas in different fields of material sciences, semiconductor devices and solid state nuclear track detectors. One such developing field is the study of heavy ions induced modifications in polymers and to understand the track formation criteria. In the present investigations an attempt has been made to compare the changes induced in the optical, structural and electrical properties of an aliphatic (CR-39) and an aromatic (Makrofol-KG) polymer by Li3+ heavy ion of energy 40MeV. UV–Vis and FTIR spectra have been analyzed to investigate the changes in the optical and structural properties of these polymers. The influence of different ions viz. Li3+ and O6+ on the same polymer Makrofol-KG is also compared. The changes in dielectric constant (ε) and dielectric loss tangents (tanδ) have also been observed.