Raman and polycrystalline IR spectra were obtained forLi2TiGeO5 and the assignment of the observed bands to the respective internal and external phononshas been proposed on the basis of lattice dynamics calculations. Temperature dependencesof Raman- and IR-active phonons are also reported to probe the paraelastic–ferroelasticphase transition that takes place at 233.5 K. This study shows that the phase transition iscontinuous and that this phase transition leads to significant distortion of the unit cell.