The recent discovery of high-temperature superconductivity in copper- based oxides is an event of major importance not only with respect to the physical phenomenon itself but also because it definitely shows that solid state chemistry, and especially the crystal chemistry of oxides, has a crucial place in the synthesis and understanding of new materials for future appli- cations. The numerous papers published in the field of high Tc supercon- ductors in the last five years demonstrate that the great complexity of these materials necessitates a close collaboration between physicists and solid...