Abstract: Reflectivity of porous silicon (PS) has been studied on unannealed fresh PS films annealed at250 °C in vacuum. The reflectance spectra of fresh PS films do not change significantly after the annealing. There are two reflection edges, the first at about 1.1 eV(1100 nm) which corresponds to the band gap of crystalline silicon. The second edge occurs at approximately 1.6eV(800 nm) which is due to absorption by the PS film. This gives an estimate of the band gap for our characterized films. It is consistent with the photoluminescence peak at 1.68 eV and suggests that similar origins, band edges, would be involved.