We present a procedure for optimization of the first and second reheat pressures in thermal power plants. The analysis is based on the first-law efficiency and exergy-balance equations. For analysis, the plant is divided into two main units (the steam generator and the turbine cycle). The results indicate that a range of first and second reheat pressures satisfy different constraints. Improvement in the plant second-law efficiency with increased reheat pressure are due to improvements in the turbine-cycle unit. Exergy destruction in the steam generator, which accounts for more than half of the exergy destruction in the power plant, is not significantly affected by reheat pressures.