This study presents the exergy and thermo-ecological performance optimization of a Gas-Mercury combined turbine system (GMCTS). Power output, power density, exergetic efficiency, total exergy destruction, ecological coefficient of performance (ECOP) and effective ecological power density (EFECPOD) are examined for the combined system. The influences of gas turbine speed, pressure ratio, air mass rate, equivalence ratio, air intake temperature and pressure of the gas turbine, residual gas fraction, mercury temperature of heat exchanger, temperature of the extracted mercury from mercury low pressure turbine (MLPT), mercury outlet temperature of the mercury medium pressure turbine (MMPT), mercury outlet temperature of the mercury high pressure turbine (MHPT) on the performance characteristics of the combined system have been examined by taking the irreversibilities and system properties into account. The results demonstrated that the component pressures and temperatures considerably affect the performance characteristics of the GMCTS. This study is novel and unique in terms of understanding of the effects of the system design and operating parameters altogether on the exergetic and thermo-ecological performance of the GMCTS.