AbstractHigh pressure powder diffraction experiments were carried out on the aluminate sodalite Sr8[Al12O24] · (CrO4)2using a miniature clamped cell with neutron radiation at the ILL and a diamond anvil cell with synchrotron radiation at Hasylab/Desy. The results of both experiments agree well. Lattice parameters were determined up to a pressure of 7.2 GPa. The average linear compressibility amounts to 4.3 · 10−3GPa−1, which corresponds to a linear bulk modulus of 233 GPa. The observation of superstructure reflections could be related to two new phase transitions. The first one occurs between 0.37 and 0.5 GPa, the second one at about 2.0 GPa. A final measurement at ambient pressure revealed the reversible character of the pressure induced phase transi