Hybrid organic-inorganic coatings based on thiol-ene systems were obtained by a UV-thermal dual-curing process. An improvement in mechanical properties and surface hardness was achieved because of the presence of the inorganic filler generated in situ via the sol-gel process. TEM analysis clearly evidenced the reduction of the nanosize dimensions of the inorganic silica domains by increasing the coupling agent content in the photocurable formulation. (C) 2009 Elsevier Ltd. All rights reserved.