Beta-Beams: present design and expected performances

We give the present status of the beta-beam study, which aims at producing intense nue and antinue beams from the decay of relativistic radioactive io ns. The emphasis is put on recent technical progress and new ideas. The expected performances in terms of neutrino mixing parameters theta13 and CP violating phase delta using a megaton water Cerenkov detector installed in the Frejus underground laboratory are shown to be excellent, and the synergy with a a companion SuperBeam is underlined.