Electro discharge machining (EDM) utilizing transferred arc plasma is widely accepted for the drilling or the molding of metals. In the present study, a new type of EDM system employing a composite electrode fabricated a narrow and deep hole (diameter: 0.70 mm, depth: 150 mm) in a steel block. The composite electrode consisted of a metal rod encased in a dielectric pipe jacket. The dielectric jacket prevents secondary discharges occurring between the sidewalls of the rod electrode and the fabricated hole, enabling fabrication of a deep and narrow hole. The system design and set-up, operation, and machining performance of the new system are. described here. (C) 2003 Elsevier B.V. All rights reserved.