Nanostructured organic-inorganic hybrid epoxy coatings containing zirconia domains were obtained via a cationic UV/thermal dual-cure process. Uniform distribution of the in situ generated zirconia within the polymeric network on a nanometric scale (5-25 nm) was demonstrated by AFM and TEM analyses. The UV-cured films showed increase of the refractive index by increasing the zirconium tetrapropoxide content in the photocurable formulation. Coatings with a drastic cut-off in the UV spectra still maintaining transparency in the visible light were achieved. These coatings could find advanced applications as antireflection coatings, or in the optical industry. (C) 2008 Elsevier Ltd. All rights reserved.