In this study, the thermoeconomic analysis of the combined cycle system with a single-pressure heat recovery steam generator is investigated. The variable parameters selected for the optimization are the compressor pressure ratio, gas turbine inlet temperature, and turbine and compressor isentropic efficiencies. The others variables are assumed constant. In the analysis, all thermodynamic and thermoeconomic expressions are formulated as a function of these decision variables. Using the computer program written in Visual Basic language, developed model has been solved and the conditions giving minimum unit electricity production cost have been determined.