We have previously reported on the AC electrical properties of Au-SiOx-Au sandwich structures prior to electroforming, while the present work is concerned with the AC properties after electroforming. The deposition conditions were optimised for easy electroforming, and conductance, capacitance and dielectric loss measurements were made in the frequency range 100 Hz to 20 kHz for temperatures in thr range 78-523 Ii. The AC conductivity showed an increase of up to six orders of magnitude above that observed in samples prior to electroforming, and also exhibited thermally-activated behaviour. Assuming a filamentary conduction process, it is argued that the conductivity of the filamentary material is intermediate between that of the electrode and the higher conductivity form of carbon, and that the filaments are probably comprised of an amorphous SiOx phase interspersed with gold and/or carbon. Up to approximately I kHz the capacitance showed an increase with increases in temperature and frequency. The capacitance was found to be essentially frequency-independent above 1 I;Hz, but sometimes showed an increase with increasing temperature. The loss tangent showed an increase of up to six orders of magnitude after electroforming. This increase indicates that a localised structural change took place, which was associated with the establishment of filaments. A simple modification to the model of Goswami and Goswami wets sufficient to account for the dielectric loss dependence on frequency after electroforming.