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The objective of the innovative high-temperature fuel nozzle program was to design, fabricate, and test Propulsion engine fuel nozzles capable of performance despite extreme fuel and air inlet temperatures. Although a variety of both passive and active methods for reducing fuel wetted-surface temperatures were studied, simplE thermal barriers were found to offer the best combination of operability, cycle flexibility, and performance. A separate nozzle material study examined several nonmetallics and coating schemes for evidence of passivating or catalytic tendencies. Two pilotless airblast nozzles were developed by employing finite-element modeling to optimize thermal barriers in the stem and tip. Operability of these prototypes was compared to a current state-of-the art piloted, prefilming airblast nozzle, both on the spray bench and through testing in a can-type combustor. The three nozzles were then equipped with internal thermocouples and operated at 1600 [degrees] F air inlet temperature while injecting marine diesel fuel heated to 350 [degrees] F. Measured and predicted internal temperatures as a function of fuel flow rate were compared. Results show that the thermal barrier systems dramatically reduced wetted-surface temperatures and the potential for coke fouling, even in an extreme environment., A program was established to design and test engine fuel nozzles capable of withstanding high fuel and inlet air temperatures. At extreme fuel and air inlet conditions, thermal barriers were found to be effective in decreasing fuel carrying tip structure temperatures and stem temperatures. Two airblast prototypes with thermal barriers on the stem and tip were tested. Comparing the results with those from existing airblast nozzles demonstrate the effectiveness of using thermal barriers.