CaTiO3 nanoparticles of 30-40 nm in size were synthesized via a polyacrylamide gel route. Ag nanoparticles with size of 8-16 nm were deposited onto CaTiO3 particles by a photochemical reduction method to yield CaTiO3@Ag composites. The photocatalytic activity of prepared samples was evaluated by degrading methyl orange under ultraviolet irradiation. It is demonstrated that Ag-decorated CaTiO3 particles exhibit an enhanced photocatalytic activity compared to bare CaTiO3 particles. After 60 min of photocatalysis, the degradation percentage of MO increases from 54% for bare CaTiO3 particles to 72% for CaTiO3@Ag composites. This can be explained by the fact that photogenerated electrons are captured by Ag nanoparticles and photogenerated holes are therefore increasingly available to react with OH-/H2O to generate hydroxyl (•OH) radicals. •OH radicals were detected by fluorimetry using terephthalic acid as a probe molecule, revealing an enhanced yield on the irradiated CaTiO3@Ag composites. In addition, it is found that the addition of ethanol, which acts as an •OH scavenger, leads to a quenching of •OH radicals and simultaneous decrease in the photocatalytic efficiency. This suggests that •OH radicals are the dominant active species responsible for the dye degradation.