Coulomb breakup of high-energy secondary beams of unstable nuclei serves in nuclear structure investigations of neutron-rich isotopes. A summary of the respective research activities at GSI is presented, covering isotopes from helium to oxygen. The breakup is mediated through dipole excitations into the continuum. Non-resonant excitations into the continuum near the dissociation threshold deliver information on the single-particle ground-state structure. Resonant excitation into the giant resonance domain is also observed. In addition, a brief outlook on future activities at GSI is given.

PACS numbers: 21.10.--k, 23.90.+w, 25.60.--t, 27.20.+n