The incorporation of photochromic dyes in mesostructured silica particles and the subsequent incorporation of the particles in latex to create solid films with relatively large, yet controllable, thickness, was recently reported [N. Andersson, P. C. A. Alberius, J. Skov Pedersen, L. Bergstroem, Microporous and Mesoporous Materials, 2004, 72, 175-183; N. Andersson, P. Alberius, J. Oertegren, M. Lindgren, L. Bergstroem, J. Mater. Chem., 2005, in press.] As photochromic dyes, spirooxazine (SO) and spiropyran (SP) were used. The films are transparent in day-light at room temperature and become coloured upon UV exposure. The films have a potential for usage as display systems, optical switches and optical memory devices. The synthesis of the SO/SP doped silica particles and the making of solid films is briefly described, and the spectral properties of SO/SP in various environments - in the film, in solution, as pristine dye powder and as silica particle powder - were studied by absorbance and fluorescence measurements, including time-resolved fluorescence decay measurements. It was found that the spectral properties of the photo-chromic dyes in the films are similar to those observed in solution, indicating that they are well-dispersed in the organic phase of the silica particles, which, in turn, are well-dispersed in the latex film.