Abstract This paper describes techniques for determining optimum plant configuration and operating conditions for complex binary cycles employing feedwater heaters, moisture separators, multi-stage compressors, and a regenerator. A model describing the efficiency of binary cycles is developed in a form suitable for optimization. As part of the optimization procedure, the system is partitioned into Brayton and Rankine portions by fixing coupling variables, and then for fixed values of coupling variables the two cycles are optimized separately. Dynamic programming is used in the Rankine portion of the binary cycle and a modified search technique in the Brayton cycle. For the range of reactor outlet and boiler saturation temperatures examined, and for boiler exit temperature up to 536°C, binary cycle efficiencies become optimum at 371°C boiler saturation temperature, 110°C to 170°C superheat, no regeneration for reactor exit temperatures below 1170K and appreciable amount of regeneration above 1170K. Optimum binary cycle efficiencies are 0.506, 0.533 and 0.560 for reactor exit temperatures of 1060 K, 1170 K and 1280 K, respectively.