Anatase TiO2 photoanodes were deposited by self-limiting growth techniques at low temperature. The optical bandgap and flatband voltage of the as-deposited films agree with the values obtained from single crystal anatase. The donor density could be increased by both UV illumination and cathodic polarization in acidic solutions. Improvements in photocurrent scaled closely with changes in carrier concentration, with over 20-fold enhancements observed over the as-deposited films. The threshold potential for hydrogen intercalation was -0.6 V vs Ag/AgCl. At this level the carrier concentration could be manipulated with no change in optical transmission. At lower potentials irreversible changes are observed which are attributed to the reduction of the underlying indium tin oxide contact. In contrast, no changes were observed when fluorinated tin oxide was used as the contact layer. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3431546] All rights reserved.