Two series of TeO2-P2O5And Bi2O3-TeO2-P2O5glass systems have been prepared for the present investigation. Measurements of the dc electrical conductivity in the temperature range of 300-573k for unirradiated and y-irradiation glass samples are reported. The dc electrical conductivity are found to increase with increasing y-irradiation doses. The observed increase in conductivity is attributed to the relative increase in the charge carriers that produced by y-rays. The radiation induced change in dc conductivity is found to be sensitive to temperature and glass composition.