 Energy and exergy efficiencies of the thermal power plant  The effects of steam parameters on the performance  The maximum exergy loss occurs in the thermal power plantIn this study, the thermodynamic analysis of the sub-critical and super-critical coal-fired power plants under various load conditions have been investigated. Figure A. Schematic diagram of the optimized coal-fired power plant Purpose: The aim of this study is to show the effect of live steam parameters on thermal and exergy efficiencies of thermal power plants under various load condition.Theory and Methods: Soma Power Plant was taken as a Base Case for this study. Steam parameters were increased from sub-critical level to super-critical level to investigate the effects of the steam parameters on the thermal and exergy efficiencies. Second reheat section, four regenerative heaters, two desuperheaters and regenerative turbine were added to optimize the power plant. Furthermore, the effects of the load condition on the plant's energy and exergy efficiencies are investigated by operating power plants under 50%, 75% and 100% load conditions. Results:It has been found that live steam parameters have a huge impact at the efficiencies under various load conditions. Conclusion:It is concluded that live steam parameters and load conditions are the most critical parameters to determine the power plants efficiencies. On the other hand, this study only includes performance analysis of the power plant. Thermoeconomic analysis of this study has to be investigated to achieve meaningful results.