Porous silicon (PS) thin films have been prepd. by electrochem. anodization of p-Si in HF-H2O-EtOH soln. and they have been used as substrate material for the prepn. of iridium oxide based electrodes (PS/IrO2) using the thermal decompn. technique. The morphol. and the electrochem. behavior of the PS/IrO2 have been studied and the results have been compared with IrO2 electrodes deposited on a sandblasted p-silicon (p-Si/IrO2). SEM analyses have revealed that the PS/IrO2 electrodes are porous, rough and IrO2 appears to be deposited within some silicon pores, while the p-Si/IrO2 present a mud-cracked' surface. Cyclic voltammetries in 1 M HClO4 have shown that the PS/IrO2 presents higher surface area than p-Si/IrO2. [on SciFinder (R)]