We study the finite temperature dynamical process followed by the D-2d singlet ground state of tetraoxygen, O-4. Born-Oppenheimer ab initio molecular dynamics (AIMD) simulations are done at near-room temperature and at 700 K using a calibrated DFT-based electronic structure description. The vibrational spectra are reported and the lowest vibrational modes are identified, which correlate well with ab initio static predictions. The largest non-harmonic contributions on the spectra are found for the modes involving nu(5)(B-1) and nu(6)(A(1)) quanta. The relative vibrational peak intensities provide valuable information for the identification of this as yet undetected stable polyoxygen species. (C) 2009 Elsevier B. V. All rights reserved.