This paper presents the performance of the world’s first Externally Fired micro Gas Turbine (EFmGT) demonstration plant based on micro gas turbine technology. The plant was designed by Ansaldo Ricerche (ARI) s.r.l. and the Thermochemical Power Group (TPG) of the Universita di Genova, using the in-house TPG codes TEMP (Thermoeconomic Modular Program) and TRANSEO. The plant was based on a recuperated 80 kW micro gas turbine (Elliott TA-80R), which was integrated with the externally fired cycle at the ARI laboratory. The first goal of the plant construction was the demonstration of the EFmGT system at full and part-load operations, mainly from the control point of view. The performance obtained in the field can be improved in the near future using high-temperature heat exchangers and apt external combustors, which should allow the system to operate at the actual micro gas turbine inlet temperature (900–950 °C). This paper presents the plant layout and the control system employed for regulating the microturbine power and rotational speed. The experimental results obtained by the pilot plant in early 2004 are shown: the feasibility of such a plant configuration has been demonstrated, and the control system has successfully regulated the shaft speed in all the tests performed. Finally, the plant model in TRANSEO, which was formerly used to design the control system, is shown to accurately simulate the plant behavior both at steady-state and transient conditions.Copyright © 2005 by ASME