AC and DC conductivities have been measured by using the real (ε′) and imaginary (ε′′) parts of the dielectric constant data of glass and glass-ceram ics (GC) at different temperatures in the  rage 297-642K and in the frequency range 100 Hz to 10 MHz. Using Anderson –Stuart model, we have calculated the activation energy, which is observed to be lower than that of the DC conductivity.The analysis for glass/glass-ceramics indicates that the conductivity variation with frequency exhibits an initial linear region followed by nonlinear region with a maximum in the high-frequency region. The observed frequency dependence of ionic conductivity has been analyzed wit hin the extended Anderson–Stuart model considering both the electrostatic and elastic strain terms. In glass/glass-ceramic the calculations based on the Anderson-Stuart model agree with the experimental observa-tions in the low frequency region but at higher frequencies there is departure from measured data.