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We present a lattice-dynamics study of rocksalt cadmium oxide (CdO). We use Raman scattering to investigate a series of high-quality CdO epilayers grown on sapphire substrates by means of metal-organic vapor phase epitaxy. Two main features are found to dominate the Raman spectra of CdO: a sharp peak at∼ 265 cm− 1 and a broad feature at∼ 390 cm− 1⁠. To assign these and other weaker second-order features that appear in the Raman spectra, we have carried out an ab initio calculation of the phonon dispersion in CdO. From the calculated two-phonon density of states (PDOS) we tentatively assign the peak at 265 cm− 1 to a 2 TA (L) mode. The broadband centered at∼ 390 cm− 1 seems to reflect the high two-PDOS in the 300–450 cm− 1 spectral region.