The features of atomic and electron structure and phase composition of the surface in the samples of macro-, micro- and nanoporous silicon and their changes with depth were investigated with the use of Xray photoelectron spectroscopy, ultrasoft X-ray emission spectroscopy and scanning electron microscopy. Analysis of the X-ray emission spectra applying the simulation method allowed to follow the trends in the changes of the composition for the investigated samples starting from the surface and into the bulk and to show the differences in the phase composition between the samples of porous silicon with different pores size. (C) 2015 Elsevier B.V. All rights reserved.