This chapter covers a wide range of applications of infrared imaging systems to combustion, from both specific and practical scientific points of view. Recent new applications are also presented in the last part. The availability of new sophisticated and flexible IR sensors makes possible the applicability of IR devices, as complementary tools, to existing techniques for combustion characterization. In fact, an IR camera allows visualization of phenomena that cannot be caught by the UV-Visible cameras. Different aspects of InfraRed imaging systems utilization are presented here from the choice of the sensor to the specific application. Particular attention is focused on the use of Fast IR Imaging of flames applied in two different types of gas turbine burners and in two traditional industrial burners. We illustrate how useful is the IR imaging device for temporally and spatially characterizing the combustion fluctuations. Finally, we discuss the undergoing developments of the application of IR-based sensors for burner control.