This paper presents the details of an experimental evaluation of the film cooling effectiveness of gaseous nitrogen and argon when injected near the nose tip of a hemispherical dome. A series of tests were conducted in the Johns Hopkins University/Applied Physics Laboratory Infrared (IR) Seeker Aerothermal Test Facility to determine the amount of coolant flow required for thermal and structural survival of an IR dome when exposed to stressing missile flight environments. The tests measured the temperature distribution over a simulated IR dome for two representative altitudes at a nominal Mach number of 5 and pitch angles of zero and 10 degrees. The key experimental result was that the entire dome can be cooled with the predicted coolant flow requirements. Reduced levels of heating into the dome was still achieved at 10% of the predicted flow. Coolant flow correlations based on a modified flat plate model were validated.