Ordered mesoporous silica films have been prepared by spin-coating using tetraethoxysilane (TEOS) as a silica source and nonionic surfactant Brij 30 as a templating agent. Sulfuric acid (H2SO4), nitric acid (HNO3), or hydrochloric acid (HCl) was mixed as a catalyst in coating solutions. A vapor infiltration treatment was performed using TEOS or trimethylethoxysilane (TMES). The vapor infiltration treatments effectively improved mechanical strength, hydrothermal stability and film adhesive. The dielectric constant of the TMES-treated mesoporous silica film was 1.8. (c) 2005 Elsevier B.V. All rights reserved.