reviewed, and the conclusions that can be drawn from these results are discussed. Problem areas that are inherent in such systems are identified. For the purposes of initially defining diagnostics requirements, two different advanced stationary power gas turbine systems are considered. System I is a low turbine inlet temperature system (LTTS) with high ash carry-over into the turbine, and System II is a high turbine inlet temperature system (HTTS) fired with a clean liquid or gaseous coal-derived fuel or incorporating an efficient interstage gas-cleanup system. Estimates of the properties of the turbine inlet flows to be expected in these systems are presented and serve as a basis from which the discussion of diagnostic techniques proceeds. Diagnostic techniques for the determination of particulate size distribution, particulate mass loading density, gas velocity, gas temperature, and species concentrations are discussed.