The infrared and Raman spectra of α-cyanoacetylacetone have been analyzed by the aid of ab initio calculations at post-Hartree–Fock (MP2) and density functional theory (DFT) levels and by considering the spectral behavior upon deuteration of the enolated proton. The results are compared with those of acetylacetone. The calculated hydrogen bond strength is 16.26 kcal/mol. It is shown that a strong interaction between C=C stretch and OH in-plane bending motions in CNAA as well as other β-diketones give rise to two Raman active lines in 1500 and 1300 cm−1 regions. The intensity ratio of these two lines could be used as criteria for the estimation of the intramolecular hydrogen bond strength in the cis-enol form of β-diketones

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