A novel platinum cavity electrode (Pt-CE) was fabricated by drilling a small circular cavity (0.5mm diameter) through a thin Pt foil (ca. 0.15mm thickness, 2.0mm width). It was used to record cyclic voltammograms (CVs) of the insulative AgCl powder (as a model) in aqueous solutions. The voltammetric response of the electrode was fast (tested to 100mV/s) and the charge under the reduction peak agreed well with the mass of the AgCl powder. Further, the CVs were featured by not only an “irreversible” reduction peak, but also linear logarithm correlations between the potential scan rate and the reduction peak current or potential. Similar results were also obtained from thin AgCl coating modified Ag disc electrodes (1.0mm diameter) formed by anodisation in chloride solutions. Based on these common electrode kinetic properties, a general explanation is proposed according to the mixed control of the electro-reduction by charge transfer at the conductor/insulator/electrolyte three phase interlines and mass diffusion through the reduction generated porous metal layer. In addition, some CVs also exhibited a minor reduction peak at less negative potentials and the origin was identified experimentally.