Photocatalysts based on TiO₂ co-doped with rare earth metal (RE) and gold nanoparticles have been prepared using a sol-gel method and followed by gold reduction. Specific surface areas of the modified photocatalysts were calculated by the Brunauer-Emmett-Teller method (BET). Diffuse reflectance spectra of the obtained photocatalysts were recorded with a UV-Vis spectrophotometer (DRS UV-Vis). The influence of the type of rare earth metal on photoactivity of Au-RE-TiO₂ nanocomposites in model reaction manifested by toluene photodegradation in a gas phase was investigated. The obtained results showed that photodegradation of toluene in the gas phase is possible over Au-RE-TiO₂ irradiated by UV or Vis light. The Au-RE-TiO₂ photocatalysts relative to undoped TiO₂, did not caused an increase of toluene degradation in the air under visible light. The samples doped with Er³⁺ or Pr³⁺ presented the highest activity in solar light among of Au-RE-TiO₂. It was observed that both metal dopants affected the surface area of TiO₂. The Au-RE-TiO₂ photocatalysts relative to undoped TiO2 exhibited the absorption properties under Vis light.