The surface layers of BDD electrodes have been roughened through excavation by small Ni, Co and Pt particles in a flowing gas mixture of H-2(10%) and N-2(90%) between 800 degrees C and 1000 degrees C. The specific surface area of the BDD evaluated with the double layer capacitance was enhanced by the excavation of up to nearly 15 times as much pristine BDD electrode. The following potential applications for the surface-roughened BDD were proposed: (1) interlayer of the porous oxide catalyst layer and metal substrate of IrO2-Ta2O5/(Ti or Nb) electrode, for instance, and (2) supporting material with large surface area for catalyst metal particles. (C) 2009 Elsevier Ltd. All rights reserved.