Photo-electrochemical synthesis of silver-oxide clathrate Ag7O8NO3 on Nb-doped SrTiO3(001) single crystal electrodes in AgNO3 aqueous solutions was studied. The formation of small plate-like grains on the electrode first occurred, followed by the growth of large faceted crystals. The selectivity for the photocatalytic oxidation products Ag7O8NO3 and O-2 was found to depend on the electrode potential. A lower electrode potential resulted in preferential deposition of Ag7O8NO3 over O-2 evolution. This result suggests that the role of the electrode potential in this photochemical process is to control the interface reaction kinetics, as well as the separation of photo-excited electron-hole pairs in bulk. (C) 2012 The Electrochemical Society. [DOI:10.1149/2.015204esl] All rights reserved.