A study of hydrogen bonding interactions in the liquid phase. Infrared absorbance data were obtained in digital form for the v(_s)(OH) band of phenol when complexed by hydrogen bond formation to each of the bases acetonitrile and 1,4-dioxan, along with the v(_s) (OD) bands of their deuterated analogues, each in carbon tetrachloride solution. Similar data were obtained for the complex formed between phenol and acetonitrile when in chloroform-d solution. The vibrational phase relaxation of the vibrational modes as related to the model, published by Robertson and Yarwood, which characterises the relaxation. Similar data for the hydrogen-bonded complex formed between phenol and pyridine in carbon tetrachloride solution and for the decoupled v(_s) (OH) and v(_s) (OD) vibrational modes of water in isotopically-dilute solutions were also obtained. Far-infrared spectral data for the complex formed between phenol and each of the bases 1, 4-dioxan and pyridine were obtained and related to the mid-infrared data. Raman spectral data for the v(_1) vibrational mode of acetonitrile when in solution in the presence of methanol-d(_4) were also obtained and interpreted in terms of the theories of vibrational phase relaxation.