Structural studies of hydrogen, oxygen and ice at very high pressures

High brilliance and high stability make the European Synchrotron Radiation Facility an ideal instrument for structural studies at very high pressures, especially for low-Z materials were high compressibility and poor scattering power are associated with very small sample volumes. We review here measurements on hydrogen, oxygen and ice VII to pressures beyond 100 GPa using single crystal and powder techniques. A brief discussion of future prospects is also included.