Li2GeO3 is an orthorhombic pyroelectric transparent crystal with space group C2v12(Cmc21). Scott et al. have shown that it can be grown easily in very large boules by the Czochralski technique. We report and discuss infrared reflectivity and Raman measurements of the lattice vibrational modes along all three polarization directions, and the optic index of refraction. The frequencies of the modes determined from the two techniques are in good agreement with each other except that several more modes are observed by the Raman techniques. The clamped-dielectric-constant values calculated from the modes are in fair agreement with our capacitance measurements. © 1974 The American Physical Society.