Nonionic alkyl poly(oxyethylene) surfactants (Brij 56) films on a silicon substrate were treated with a tetraethoxysilane (TEOS) vapor. Mesostructured silica films were formed through a nano-phase transition under the infiltration of TEOS into the surfactant films. It was found that the calcined film had a 3D pore structure from the field emission scanning electron Microscope (FE-SEM) observations in a different orientation. Grazing angle of incidence small angle X-ray scattering (GISAXS) measurement results showed that the symmetry of the film was an Fmmm space group oriented with the (010) plane parallel to the Surface. The ordered structure of the films showed higher thermal stability than the films prepared by a conventional solvent-evaporation method. (C) 2008 Elsevier Inc. All rights reserved.