In this study, the effect of condenser pressure on condenser area and the thermoeconomic parameters is investigated. The objective function of the thermoeconomic optimisation is to minimise the production costs per unit of electrical output and to maximise the annual cash flow of the power plant. Therefore, the thermoeconmic parameters are generated for different range of condenser pressure. The case 283 MW combined cycle gas turbine (CCGT) power plant with typical design of commercial combined cycle power plant was demonstrated as an example. The optimised combined cycle was compared with a regular CCGT plant. The results indicated that the thermoeconomic optimisation procedure used in this study led to a significant improvement for the economic parameters, where the annual cash flow was increased by 1.1 M$, and the production cost of electricity was decreased by 0.043 cent-dollar per kilowatt-hour.