The object of this proposal is to determine, by using neutron diffraction, the nature of the polyamorphic phase transition that occurs in glassy GeO2 with increasing pressure. Motivation for a new experiment on PEARL is provided by the results that we have recently taken for the structure of glassy GeO2 at pressures up to 8 GPa by using D4C at the ILL. The new experiments on PEARL will extend the pressure range up to 25 GPa and will thus enable the full range of the transition to be observed from a tetrahedral to an octahedral glass. The results will help to elucidate the mechanism by which the structural transformation occurs and will characterise densification mechanisms in the octahedral phase.