Mesostructured thin films are known to form at the interface between either air or a solid surface. and a dilute acidic solution containing the silica precursor, and surfactant template. These films are transparent, and, when grown at the air/solution interface, self-supporting. We have been studying the formation processes of these films to try to understand and thus control the formation of both the mesoscale and the macroscale structure. The films are characterised using a variety of in situ methods including X-ray reflectivity techniques and Brewster angle microscopy, to study both the large and small scale structure development processes. As a result of our investigations we have suggested a coacervation driven mechanism for film growth and application of this understanding now drives our further development of these films. Here we present results concerning the effect of surfactant headgroup type, structure and counterions on the development of well-organised mesostructures, and also on the macroscopic film characteristics. (c) 2005 Elsevier B.V. All rights reserved.