Abstract The sodium salts of the bisboranohypophosphite anions H 2 P(BH 3 ) 2 − , D 2 P(BH 3 ) 2 − , and H 2 P(BD 3 ) 2 −1 have been studied as solids and as aqueous solutions by infrared and Raman spectroscopy. Correlation of these data, including Raman depolarisation ratios, has enabled detailed assignments to be made of most of the vibrational modes. An approximate P-B bond force constant has been calculated. In addition, proton- and 11 B-NMR data are presented and assigned for each of the molecules.