A macro-porous silica film served as mechanical support to immobilize TiO2 nanoparticles, which were doped with erbium. The films and the nanoparticles were prepared by sol-gel route. The nanoparticles exhibited photocatalytic activity under visible light. We obtained a degradation rate of methylene blue that followed first order kinetics. The sensitization of the nanoparticles to visible light was attributed to a red shift in the band-gap of the TiO2 due to the addition of erbium ions. (C) 2011 Elsevier Ltd. All rights reserved.