Orthorhombic beta-LiScGe2O6 single crystals were compressed hydrostatically up to 10.35 GPa using a diamond anvil cell and investigated in situ by means of X-ray diffraction and Raman spectroscopy. Crystal-structure investigations at ambient conditions and at high pressure show a structural transition from an orthopyroxene-type Pbca structure (a approximate to 18.43 angstrom, b approximate to 8.85 angstrom, and c approximate to 5.34 angstrom at 8.6 +/- 0.1 GPa) to a postorthopyroxene type P2(1)/c structure of the new dense gamma-LiScGe2O6 (a approximate to 18.62 angstrom, b approximate to 8.85 angstrom, c approximate to 5.20 angstrom, and beta approximate to 93.1 degrees at 9.5 +/- 0.1 GPa). The structure refinements reveal displacive shifts of 0 atoms associated with a rotation of every other tetrahedral-chain unit from the O- to S-type position similar to the postorthopyroxene-type MgSiO3. As a consequence of the oxygen displacement, the coordination number of Li atoms is changing from [S + 1] to a proper 6-fold coordination. The transition around P, = 9.0 +/- 0.1 GPa is associated with a volume discontinuity of Delta V = -1.6%. This orthopyroxene (OEn-Pbca) to postorthopyroxene (pOEn-P2(1)/c) transition is the second example of this type of transformation. Precise lattice parameters have been determined during isothermal compression. The fit of the unit-cell volumes of beta-LiScGe2O6, using a third-order Birch-Murnaghan equation of state, yields V-0 = 943.63 +/- 0.11 angstrom(3), K-0 = 89.8 +/- 0.6 GPa, and dK/dP = 4.75 +/- 0.18 as parameters. Evaluation of the data points beyond the critical transition pressure using a second-order Birch-Murnaghan equation suggests V-0 = 940.6 +/- 4.4 angstrom(3) and K-0 = 82.4 +/- 4.8 GPa. A series of high-pressure Raman spectra confirm the symmetry-related structural transition, with band positions shifting in a noncontinuous manner, thus confirming the proposed first-order transition.