CP violation in B decays to charmonia at LHCb

B-(s)(0) meson decays to states containing a charmonium meson are theoretically clean modes to measure the weak mixing phases /d and Os, one of the key goals of the LHCb experiment. The current status of measurements of these observables performed by the LHCb collaboration is presented. The future perspectives, as well as the expected precision that will be achieved from LHCb, are also discussed.