Surface methylated and Pt nano-dotted single crystal n-Si (1 1 1) electrodes yielded efficient photocurrent density (j) vs. potential (U) characteristics for more than 6 h in a highly corrosive electrolyte of aqueous 8.6 M HBr + 0.05 M Br-2. On the other hand, H-terminated and Pt nano-dotted n-Si electrodes degraded seriously in about 15 min. Surface methylated but non-Pt-dotted n-Si electrodes yielded only poor j-U characteristics with low V-oc. The results clearly show that a combination of surface alkylation and metal nano-dot coating is an effective way to obtain efficient and stable Si photoelectrodes and hence photoelectrochemical solar cells. (C) 2004 Published by Elsevier B.V.