Photocatalytic synthesis of silver-oxide clathrate Ag7O8NO3 was investigated. The process is based on photocatalytic enhanced oxidation of Ag+ in a AgNO3 aqueous solution using a titanate-based photocatalyst (SrTiO3) single crystal. By doping the crystal with Nb or La, the photocatalytic production of Ag7O8NO3 is enhanced even for relatively low concentrations of AgNO3 aqueous solutions and more with higher Nb doping. This photocatalytic reaction can be understood in terms of selectivity of the oxidation reaction, favoring generation of O-2 or Ag7O8NO3, with the Nb doping as well as the concentration of the AgNO3 aqueous solution having strong impact on the reaction selectivity. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3503581] All rights reserved.