Material research problems towards a Ti-based tandem membrane with corrosion resistant TiO2 surfaces for direct light-induced hydrogen generation are outlined. Since doping of TiO2 with C and N interferes with oxygen evolution via the radical pathway, oxygen evolution via the 4-electron pathway has to be explored. For this purpose the incorporation of suitable catalysts into the TiO2 is necessary, which have to collect holes from gap states. A model of the membrane in form of a CIS solar cell in series with the anodic TiO2 photoreaction and the cathodic hydrogen evolution at a Pt-wire was tested to be active. UV- and visible light photocurrent imaging and differential electrochemical mass- spectroscopy as well as surface photovoltage measurements are used to investigate material and system properties. (c) 2006 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.