The effect of surface atomic structures on the electron spectrum and luminescent properties of porous silicon (por-Si) has been studied by methods of photo-luminescent, UV photoelectron, IR Fourier-transform spectroscopies, and mass-spectrometry. The luminescence spectra of por-Si free from carbon-containing contaminants exhibit two emission bands (hv_max = 1.81 and 1.95 eV) due to the electron-hole radiative recombination on surface states with the energy of 1.75 and 2.0 eV below the Fermi level. These states are associated with silicon hydride groups SiH_n (n = 1-3). The replacement of these groups by oxyhydride O_xSi-H and Si-O-Si structures gives the non-radiative recombination centers of dangling bond type with the energy level of 1.0 eV below E_F, thus attenuating or quenching the photoluminescence.