The paper describes some of the improvements that have been achieved, both experimentally and theoretically, in reluctance motors with purely segmental rotors. These improvements result from incorporating a shallow axial channel in the centre of the air-gap face of each segment, filling of this channel with conducting material, shaping of the ends of the segments and optimisation of the significant design parameters. It is shown that, when synchronising duties are light, the maximum pullout torque of a reluctance machine can exceed the breakdown torque of the equivalent induction machine (so that its pullout power considerably exceeds the breakdown power of the induction machine) and that maximum power factors better than 0.8 are possible. Careful attention is given to the asynchronous-performance characteristics, with particular reference to the synchronisation of load inertias of two to three times the rotor inertia (the most usual values). It is found that pullin powers greater than 90% of the induction-motor full-load powers and power factors up to 0.74 are possible. Of considerable importance, particularly in connection with thyristor-invertor supplies, is the fact that starting currents are low—about four times full-load current. Efficiencies up to 90% may be expected, even in relatively small machines. The development on the theoretical side includes (a) the generalisation of earlier results to include the effects of the channel in, and the end shaping of, the magnetic segments, and (b) the elimination, through the consideration of harmonics of permeance and rotor potential, of the need for an empirical factor in calculation of the quadrature-axis reactance. Stator-winding harmonics are considered, but it is shown that their effects are small. It is also found that losses due to the generation of high-frequency currents are small. Calculated and measured values for both reactances and synchronous-performance characteristics are shown to agree very closely over the whole range of parameters. The performances claimed here have been fully confirmed by tests on a commercial machine of approximately 10hp rating.