With the popularity of natural gas for power generation, it is not surprising that people keep inquiring about Open Cycle Gas Turbine (OCGT) and Combined Cycle Gas Turbine (CCGT) systems. But as with all products, each of these systems has its pros and cons. The OCGT has a rather straightforward operation that starts with fresh ambient air entering the compressor and ends with power generation as shown in Figure 1 below. This simplicity gives to OCGT several advantages over CCGT. However, do not get it all wrong; this cycle has also some drawbacks that may hinder its application in certain circumstances. Considering all these facts, when are open cycle gas turbines the right option?