Electrical characterization of materials, including polymers has been performed using Electrical Impedance Spectroscopy. The impedance (Z) spectra gives details about the dielectric dispersion of the resistivity (or conductivity) and the relative permittivity of the material with frequency. This enables one to assess the condition of the material, such as the ripening of fruit, or the aging of polymeric insulators. In this research, Autolab/PGSTAT30 Impedance analyzer was used to assess the aging of 28kV Thermoplastic elastomeric (TPE) insulators under multistress acid rain conditions. The aged samples showed increased conductance compared to virgin. However, the imaginary Z value (corresponding to the capacitive reactance) of the aged samples were lower than the virgin sample values. The reduction varied for HV and LV samples. The results indicate that impedance spectroscopy can be effectively used to study surface structural modification caused by aging.