The presence of C-H… O hydrogen bonds in liquid cyclohexanone is concluded from a combined theoretical and vibrational spectroscopic study. The two bands present in the nuC=O region, clearly observed in the Raman spectrum, are assigned to ‘free’ and ‘bonded’ carbonyl groups from their temperature-dependent and solvent-dependent relative intensities. In addition, a band exhibiting the same intensity dependence in the nuC-H region is tentatively assigned to the blue-shifted nuC-H… (O) mode.