By combining the techniques of dielectric relaxation spectroscopy (DRS), measurement of both ac and dc conductivities, Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM), we have explored the effect of electrical ageing on poly (methyl methacrylate) (PMMA) films at temperature between 0 °C and 80 °C in the frequency range of 1 Hz–107 Hz. These results are discussed and correlated to FTIR and SEM observations.