Pointing accuracy is a key requirement in communication satellites and Earth observation missions. Attitude control systems must guarantee tracking of the reference attitude and angular rate, while accounting for mission performance indexes such as fuel consumption and actuator wear. In this paper, an MPC-based attitude control scheme is proposed for an all-electric spacecraft using cold gas and resistojet thrusters as on/off actuators for attitude control. This technology imposes restrictions on the number of thruster firings, which are explicitly taken into account in the MPC formulation and suitably traded-off with fuel consumption. The performance of the proposed attitude control system is demonstrated on a GEO mission and compared with other control schemes involving on/off actuators.