In this paper a thermoeconomic analysis and optimization of micro gas turbines (MGT) up to 500kWe is presented. This analysis is strongly related to the need of minimizing specific capital cost, still high for MGT large market penetration, and optimizing MGT size to match market needs.The analysis was carried out for both existing regenerative MGT cycles and new inter-cooled regenerative cycles, using the Web-based ThermoEconomic Modular Program by the University of Genoa. The attention is mainly focused on the basis of thermodynamic, geometric and capital cost parameters of the main MGT devices (such as recuperator size, material and effectiveness, turbine inlet temperature, and compressor pressure ratio) and on economic scenario (fuel cost, cost of electricity, etc.) for different MGT size in the range 25–500kWe.