A number of important practical problems must be dealt with in developing a system capable of combusting syngas, particularly if the system must also emit low levels of CO and NOX emissions (Richards et al., 2001). This chapter focuses upon combustor operability issues, associated with having the combustor reliably hold the flame so that it neither flashes back nor blows out, and burns the fuel in a quiet, steady fashion. These operability issues generally involve complex, poorly understood interactions between swirling flow dynamics, flow field alterations induced by volumetric expansion across the flame, and flame propagation. The objective of this chapter is to review understanding of the manner in which syngas fuel composition influences these operability issues in steady flowing combustors, such as gas turbines, boilers, and furnaces. The four most critical of these operability issues, all of which are strongly influenced by fuel properties, are blowout, flashback, combustion instability, and autoignition.