Ag 0 /Ag + /TiO 2 composites were prepared via alkalescent hydrothermal process in aqueous ammonia, and Ag + /TiO 2 was prepared by eluting the Ag 0 cluster from the Ag 0 /Ag + /TiO 2 composites with K 3 [Fe(CN) 6 ]/aqueous ammonia. Methyl orange (MO) and Rhodamine B (RhB) were used to test the photocatalytic activity of the photocatalysts. The photocatalytic activity of the composites was greatly improved after eluting Ag 0 clusters from the Ag 0 /Ag + /TiO 2 composites. Interfacial lattice Ag + cations but not Ag 0 clusters are responsible for improving the photocatalytic performance of the composites in this work. XPS measurement shows that the chemical state of the interfacial lattice Ag + cation is different with the surface chemical adsorbed Ag + cation. Surface chemical adsorbed Ag + cation is invalid to promote the photocatalytic activity of TiO 2 while Na + cation can cancel the promotional effect of the interfacial lattice Ag + cation by competitively occupying the interfacial lattice defects. The 2h turn over numbers of the interfacial lattice Ag + cations to the degradation of MO and RhB reach 8 and 10, respectively, which show that the interfacial lattice Ag + cations act as recyclable catalytic sites but not one-time consumptive species.