We discuss a scenario in which at least some Gamma Ray Bursts are due to the transition from an Hadronic Star into a Star containing deconfined Quark Matter. The transition can take place immediately after a gravitional collapse, helping the Supernova to explode, or it can be delayed and the Supernova Explosion and the Gamma Ray Burst are then temporally separated. We discuss possible signatures of this model and the relevance of the formation of diquark condensates in order to increase the energy released. "GAMMA-RAY BURSTS FROM DELAYED COLLAPSE OF NEUTRON STARS TO QUARK MATTER STARS". Astrophys. J. 586:1250-1253,2003. "EFFECTS OF COLOR SUPERCONDUCTIVITY ON THE STRUCTURE AND FORMATION OF COMPACT STARS". Phys.Rev.D69:057505,2004.