The photoelectrochemical measurements of p-Si and porous silicon in 0.1 M H(2)SO(4) were done. The band gap of Si is a bit low for efficient hydrogen production. The silicon was made porous to improve the efficiency of hydrogen production. The porous silicon photocathodes show a substantial improvement in the hydrogen production compared to that of p-Si photocathodes. Studies were done by applying different light flux on the porous silicon. (C) 2002 International Association for Hydrogen Energy. Published by Elsevier Science Ltd. All rights reserved.