In this paper a terminal sliding-mode adaptive control scheme for robotic manipulators designed following an energy-based approach is presented. The control comprises two basic terms: a composite adaptive term which implements a feedback law for compensating the modelled dynamics and a non-linear sliding-mode term for overcoming the unmodelled dynamics and perturbations. The resulting closed-loop system is proved to be stable and it is also shown that the trajectory-tracking error converges to zero in finite time. Moreover, an upper bound of this error convergence time is calculated. Finally, the design is evaluated by means of simulations.