Mesoporous materials are characterized by the density of empty or filled pores which modulates their properties, in particular, optical properties. Although pores scatter light, the scattered energy or reflectance spectra of a mesoporous layer show a behaviour that can be attributed mainly to interference created by the interfaces; however, coherent scattering is still present inside the mesoporous layer. In this paper, we show that diffusively reflected light created by the pores depends on their distribution and shape. If they are distributed along a periodic lattice, the structure factor modulates the optical properties and the form factor that describes the geometry of the pores, influences the shape of optical spectrum. We study the influence of the form factor of pores which renders possible a tuning of the optical reflectance spectrum through pore geometry. (C) 2007 Elsevier B.V. All rights reserved.