Vibrational spectra of tetrakis(acetato)diaquadicopper(II) complex have been deeply examined in order to provide a detailed description of dynamics of [Cu(2)O(8)C(4)] core being a typical structural unit of most copper(II) carboxylates. Low frequency bands related to significant motions of metal atoms were detected by metal isotope substitution. Observed spectra and isotope shifts were reproduced in DFT calculations. For clear presentation of computed normal vibrations, a D(4h) symmetry approximation was successfully applied. Basing on observed isotope shifts and calculation results, all skeletal vibrations have been analyzed including normal mode with the largest Cu...Cu stretching amplitude assigned to Raman band at 178 cm(-1).