For the purpose of applying electro-contact discharge dressing (ECDD) to a bronze-bonded diamond grinding wheel with fine grain size, single-pulse electric discharge experiments and the ECDD experiments utilizing a conductive resin bonded GC abrasive cup-wheel as the single electrode are carried out. From the results of the experiments, it is found that an electric discharge occurs when the electrode approaches the bronze bond at a distance of 3 to 5 μm. This means that the minimum grain size of the diamond grinding wheel applicable to the ECDD is limited to 6 to 10 μm. The utilization of water-soluble coolant causes a leakage current between the electrode and the grinding wheel so that the dry ECDD without a coolant should be applied in order to realize a satisfactory electric insulation. An open circuit voltage lower than the arc voltage of 20 V should be applied in order to maintain a constant discharge pulse frequency during ECDD. From the surface plunge grinding of aluminum oxide ceramics and an optical glass, it is found that the grinding wheel after ECDD gives a better finished surface roughness than that dressed by a GC abrasive cup wheel.