An electrode assembly for a plasma reactor, such as a plasma etch or plasma-enhanced chemical vapor deposition reactor, comprises an electrode plate having a support frame attached to one surface thereof. The electrode plate is composed of a substantially pure material which is compatible with a particular reaction being performed in the reactor, while the support frame is composed of a material having desirable thermal, electrical, and structural characteristics. The support frame is bonded to the electrode plate using a bonding layer, usually a ductile metallic bonding layer, which provides effective thermal and electrical coupling while permitting a degree of thermal expansion mismatch between the support frame and the electrode plate.