The aim of this paper is to present results of investigations of different metal-oxide semiconductors for photoelectrochemical conversion of solar energy obtained in Armenia. Possible ways to increase the photocatalytic activity of semiconductor photoelectrodes are analyzed. It is shown that the development of new compact photoelectrodes made of solid solutions and more complicated multi-component compositions is most promising. Some possibilities to use porous and nanocrystalline oxide photoelectrodes in photoelectrochemistry are also discussed. Photoelectrolysis setups for the photoelectrochemical conversion of solar energy into hydrogen realized in Yerevan are briefly described. (C) 2005 Elsevier B.V. All rights reserved.