Because of their high theoretical conversion efficiencies, narrow band gap semiconductors (e.g. Si, GaAs, InP) are most suitable for photoelectrochemical solar energy conversion. unfortunately, they are destroyed by anodic dissolution (photocorrosion) in aqueous electrolytes parallel to photooxidation of electrolyte components. The coating of the semiconductor by a transparent, conductive film is one possibility for corrosion protection. We investigated the suitability of indium tin oxide (ITO) films deposited by different sputter techniques onto n-silicon and n-gallium arsenide substrates. First, the influence of the preparation conditions and of the post deposition annealing treatment on the photovoltaic properties is discussed. Second, the photoelectrochemical properties of the n- semiconductor/ITO electrodes in different aqueous electrolytes containing different redox systems are investigated. n-Si/ITO samples produced by the reactive magetron sputtering technique show the expected corrosion protection behavior, especially in electrolytes with reversible redox systems (e.g. Fe(CN)63-/4-). ITO films deposited by different sputter techniques (reactive magnetron sputtering, d.c. sputtering in different atmospheres) onto n-GaAs are not suitable for corrosion protection purposes. The low Schottky barrier at the n-GaAs/ITO interface and pinholes in the ITO layer are responsible for this behavior. The differences in photoelectrical and photoelectrochemical behavior and in corrosion stability are discussed.