Specifically labeled NaBD3H has been synthesized and characterized using X-ray diffraction, NMR, and vibrational spectroscopy. The isotopic purity of the compound, as estimated from NMR spectra, was found to be about 85% with the compound NaBD2H2 as the second product. IR spectra confirm the relatively strong intensity of the single B−H stretching mode predicted from DFT calculations. Anharmonic DFT calculations show that for the BD3H− ion Fermi resonances with the single B−H stretching mode are very limited, making this mode a promising structural probe for complex borohydrides which can be prepared by metathetical reactions.