The Fourier transform infrared and Raman spectra of newberyite, MgHPO4·3H2-O, were studied in the 2000-370 cm-l region. Also investigated were the spectra of a series of partially deuterated analogues. By comparing the spectra recorded at room temperature and those obtained at the boiling temperature of liquid nitrogen and by studying the spectra of the series of partially deuterated newberyite an assignment was proposed for the observed bands. The spectra are fully in line with the crystallographic data and prove that the title compound is a true crystalline hydrate and does not contain H3O+ions in its structure.