Using a hydrodynamic model of protogalactic evolution, we explain the amount of iron in rich clusters, deduced from X-ray observations. In fact, our calculations show that a strong shock wave originates in the first violent collapse phase and leaves the protogalaxy, carrying out a substantial fraction of its mass, with roughly solar metallicity and high temperature (107–108 K). We also show that hot material ejected from proto-cD galaxies can probably explain the observed X-ray emission in clusters.