Time-dependent CP-violation measurements allows to determine the mixing-induced CP-violating phases phi_s and beta. The measurement of the phase phi_s in the Bs-Bsbar system is one of the key goals of the LHCb experiment. It has been measured at LHCb exploiting the Run I data set and using several decay channels. In particular, the most recent Run I results that will be presented at this conference, have been obtained analyzing Bs0->J/psi(->mu+mu-) K+K- candidates in the mass region above the phi(1020) resonance and Bs0 -> Psi(2S) phi candidates.
Moreover, new results of time-dependent CP violation studies of b->ccbar d/s decays by the LHCb experiment are presented. Namely, a new measurement of CP-violation in the B0-B0bar system using B0->psi(2S) KS0 and B0->J/psi(->e+e-) KS0 decays with Run-I data sample will be shown for the first time.