The electrocyclone is an adaptation of a conventional cyclone in which a high-voltage electrode, inside the cyclone, charges the dust particles and provides an electric field which augments the inertial forces driving particles to the cyclone wall. Since the electric field forces do not decrease as the cyclone is made larger, a large (6 to 10 ft) electrocyclone can achieve collection efficiencies comparable to a one or two-ft diameter conventional cyclone. A major result of the Electrocyclone Development Program has been the development of a new high-flow cyclone design. A series of experiments were conducted in which the cyclone dimensions were systematically varied to assess their influence on collection efficiency. As a result, a high-flow cyclone was developed in which the exhaust tube diameter and its penetration into the cyclone were increased. This, plus the addition of a large high-flow inlet scroll, resulted in a cyclone which has four times the flow capacity of conventional high efficiency designs for a given diameter. The efficiency is comparable to conventional designs and the increase in pressure loss was a modest 38%. The ability to handle increased throughput decreases system costs. The electrocyclone was, therefore, reconfigured to include the new high-flow features. At the conclusion of the Electrocyclone Development Program, technical uncertainties regarding the performance of both conventional and electrostatically enhanced cyclones were substantially resolved. Early hopes that New Source Performance Standard for particulate emissions could be met with electrocyclones were not supported by the extensive experimental results. The consequent need for additional stack gas cleanup after the gas turbine is a major disadvantage in cost and complexity relative to other hot gas cleanup devices under development.