Photocatalytic activity of Ag/TiO₂ composites obtained by photoreduction treatment (PRT) was investigated. The composite materials, containing 1.0 and 2.1 wt% of silver nanoparticles were obtained by depositing silver on the Evonic–Degussa P25 titania surface. Ag/TiO₂ samples were examined by SEM, XPS and BET techniques. The XPS measurements revealed that silver particles were obtained mainly in metallic form. The photocatalytic activity of pure P25 and Ag/TiO₂ composites was compared in photooxidation reaction of some model compound like: formic acid (FA), rhodamine B (RhB) and methylene blue (MB). Photodecomposition reaction was investigated in a batch reactor containing aqueous suspension of a photocatalyst illuminated by either UV or artificial sunlight (halogen lamp). The tests proved that small amount of silver nanoparticles deposited on titania surface triggers the increase in photocatalytic activity, this increase depends however on the type of substrate. The relation between the type of substrate and the activity of the composite was discussed.