We have studied the frequency dependent conductivity of thesemiconducting cadmium vanadate glasses of compositionsxV2O5–(1−x)CdO where x = 0.6, 0.7, 0.8 and 0.9 in the temperature range 93–423 K and in the frequency range10 Hz–2 MHz. We have observed sub-linear frequency dependence and weak temperaturedependence of the ac conductivity. We have analyzed the experimental results in theframework of various theoretical models based on quantum mechanical tunneling andclassical hopping over barriers. It has been observed that the temperature andfrequency dependence of the ac conductivity is consistent with the overlapping largepolaron tunneling model, while the classical barrier hopping models fail to interpretthe data.