A design method is presented based on pinch technology and exergy analysis to reduce heat transfer irreversibility of the feedwater heaters network in steam power plants. In order to show the effects of this method, an extensive study was performed on four steam power plants. The results show that applying this method can decrease the fuel consumption and the condenser load. It also increases the boiler, the feedwater heaters network, and the turbine exergetic efficiencies. On the whole, the results show that applying this method, with a target pinch temperature of 3 degrees C, increases the cycle 2nd law efficiency 0.3-1.3% and the fossil fuel consumption decreases about 64 X 106 kg annually for 8000 operating hours per year of the studied steam power plants. Copyright (c) 2007 John Wiley & Sons, Ltd.