Distorted 3D hexagonal (space group R-3m) mesoporous titania thin films with high visible-light transparency are produced by introducing a small amount of 1-butanol into sol-gel coating sols containing P123 as the primary pore template. The mesostructure of the titania thin films identified by grazing incidence small angle x-ray scattering (GISAXS), transmission electron microscopy and scanning electron microscopy has rhombohedral symmetry (space group R-3m) with the [111] direction normal to the substrate. In the absence of butanol at the ratio of P123:titania used, poorly ordered films which may contain 2D or 3D hexagonal domains form, but introducing as little as a 1:10 ratio (by mass) of 1-butanol to P123 (with ethanol as coating solvent) leads to a well-defined 3D hexagonal structure in the resulting films. Simulated GISAXS patterns obtained using the NANODIFT program confirm the assignment of the experimental patterns to this structure. The characterization results indicate that over a 1-butanol:P123 mass ratio of 0.1 to 2, the films are composed of ordered arrays of cage-like cavities, and that in contrast to the hypothesized role of butanol as a swelling agent, the pore size decreases with an increase in the ratio of 1-butanol to P123. (C) 2011 Elsevier B.V. All rights reserved.