Abstract Inelastic scattering spectra of Aluminium hydride (AlH3)n have been measured before and after the application of a hydrostatic pressure up to 50 kbar. Some fine structure peaks were observed. The results is compared with Roszinski's infrared spectrum, in the range from 600 to 1700 cm-1. They are in general agreement. Besides, three other peaks were observed, which are difficult to measure with infrared in lower frequeacy range. It seems that this material does not change in its thermodynamic character and microstructure after hydrostatic pressure treatment.