Raman spectroscopy technique has been successfully used to study the microscopic nature of structural and/or morphological properties of investigated nanopowders. The phonon confinement model has been applied for the estimation of nanocrystals dimensions (TiO2 and CeO2), as well as the correlation length (ZnO), from the frequency shift and asymmetrical broadening of Raman optical phonon modes. The particle size distribution in nanopowders has been estimated from the low frequency Raman spectra, using the fact that the acoustic phonon modes in nanosized TiO2 and CeO2 can be well described by the elastic continuum model. In addition, the appearance of surface optical phonon modes has been predicted theoretically by the dielectric functions approach and detected experimentally in the Raman spectra of ZnO nanopowders, whereas the resonant behaviour of the first and second order ZnO Raman modes has been used for estimation of the electron-phonon interaction in this kind of nanomaterial. The optical properties of oxide nanopowders have been investigated by spectroscopic ellipsometry and photoluminescence spectroscopy. It has been shown that bandgap energy, as well as the energies of the other interband electronic transitions in investigated nanopowders can be determined by spectroscopic ellipsometry. On the other side, the existence of the broad bands in visible region of the photoluminescence spectra of TiO2 and ZnO nanopowders points out to the various electronic transitions mediated by defect levels within the bandgap.