Electronic spectra of porous Si have been investigated in the region <4 eV below the Fermi level with specimens subjected to in-situ oxygenation and thermal treatments. The measurements were made with a UHV photoelectron spectrometer using "soft" energy (hv=8.43 eV) excitation of the photoemission. The significance of the density of occupied states to the photoluminescence and its degradation in porous Si is discussed. Fine structure of the photoelectron spectra is found from specimens heated in oxygen at 600 K.