This paper addresses a robust tracking control of an autonomous underwater vehicle-manipulator system (UVMS) based on terminal sling mode control in task space along with a disturbance observer. The effectiveness of the proposed scheme is demonstrated using numerical simulations having a serial planar manipulator (two rotary joints) on an underwater vehicle in a horizontal plane. An inverse dynamic solution for the system is obtained using the Newton-Euler method incorporating hydrodynamic and dynamic coupling effects. Performance of the proposed scheme is compared under various control schemes and demonstrated numerically for a predefined trajectory of the end effector (in task space). © 2015 ACM.