Abstract: Both wire and porous AgO electrodes were studied using photoelectrochemical method during their cathodic polarization. Much information has been available through their photoresponse measurements. The maximum open-circuit photopotential ΔV_(Ph, oc) occurred at the moment when the surface of electrode was fully covered with Ag_2O and dendritic Ag was just about to appear. The ratio of ΔV_(Ph, oc) for these two electrodes may be related to the pore configaration of the porous electrode. The photoresponse waveforms of n-p-n transition were first seen by means of signal averaging technique.