Post-irradiation studies on poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) have been carried out to elucidate the effects of gamma-radiation on the electrical conduction mechanism. Irradiation was performed in air at room temperature by use of a Co-60 gamma source at different dosages. The electrical conductivity of PPO was studied in a metal/polymer/metal sandwich configuration in the temperature range of 298-353 K and the applied voltage range of 100-2000 V. No change in the conduction mechanism was observed when compared to unirradiated PPO. However, the magnitude of the current gradually decreased from 3.6 x 10(-12) A for unirradiated PPO to 6.5 x 10(-13) A for the sample irradiated with the maximum dose (0.60 MGy). The irradiated PPO has been characterized for its chemical structural changes using wide-angle X-ray diffraction, differential thermal analysis, high-performance liquid chromatography and Fourier-transform infra-red (FTi.r.) spectroscopy techniques. A degradation mechanism is postulated based on FTi.r. results. The dose-dependent changes in electrical conduction have been discussed on the basis of decrease in average molecular weight and changes in the chemical structure of PPO.