Synchronous machines with superconducting field windings offer reduced losses, size and weight. Continuous advances in the HTS conductor development at American Superconductor Corporation enable the demonstration of machines with increasing power. The latest achievements include a > 200 h.p. (150 kW) motor operated on an inverter, built and tested at Reliance Electric Corporation, and coils for a 1 MW generator for airborne applications. The HTS coils provide MMFs of the order of 70 000 A turns per pole and operate between 20 and 27 K. At this temperature, gaseous helium or hydrogen is used as the coolant. The cooling is more efficient by a factor of 10 than for cooling systems required for LTS materials operating at liquid helium temperatures. The elevated operating temperature offers significant benefits for the overall efficiency as the coefficient of performance for removing the parasitic heat load (cryostat and current lead loss) is improved. On this path to commercially viable machine sizes, American Superconductor currently is developing and manufacturing HTS coils for a 1000 h.p. (750 kW) synchronous motor which will be delivered to Reliance Electric for demonstration in 1998.