Silver nanoparticles were homogenously dispersed on titania nanotubes (NT), which were prepared by alkali hydrothermal methodology and dried at 373 K. Ag+ incorporation was done by impregnative ion exchange of aqueous silver nitrate onto NT. First, Ag+ ions incorporate into the layers of nanotube walls, and then, upon heat treatment tinder N-2 at 573 and 673 K, they migrate and change into Ag2O and Ag-0 nanoparticles. respectively. In both cases, Ag nanoparticles are highly dispersed, decorating the nanotubes in a polka-dot pattern. The Ag particle size distribution is very narrow, being ca. 4 +/- 2 nm Without any observable agglomeration. The reduction of Ag2O into Ag-0 octahedral nanoparticles occurs spontaneously and topotactically when annealing, without the aid of any reducing agent. The population of Ag-0 nanoparticles can be controlled by adjusting the annealing temperature. An electron charge transfer from NT support to Ag-0 nanoparticles, because of a strong interaction, is responsible for considerable visible light absorption in Ag-0 nanoparticles supported on NT.