[en] Using synchrotron angle-dispersive x-ray diffraction (ADXD) and Raman spectroscopy on samples of Li₂O pressurized in a diamond anvil cell, we observed a reversible phase change from the cubic antifluorite (α, Fm-3m) to orthorhombic anticotunnite (β, Pnma) phase at 50(±5) GPa at ambient temperature. This transition is accompanied by a relatively large volume collapse of 5.4 (±0.8)% and large hysteresis upon pressure reversal (P_down at ∼ 25 GPa). Contrary to a recent study, our data suggest that the high-pressure β-phase (B_o = 188 ± 12 GPa) is substantially stiffer than the low-pressure α-phase (B_o = 90 ± 1 GPa). A relatively strong and pressure-dependent preferred orientation in β-Li₂O is observed. The present result is in accordance with the systematic behavior of antifluorite-to-anticotunnite phase transitions occurring in the alkali-metal sulfides