A porous radiant burner testing facility was built, consisting of temperature and gas composition measurements as a function of position, as well as spectral and total radiosity measurements. Uncombusted hydrocarbons were detected within the flame support layer for only low flow rates (e.g., 71 L / min for a reticulated ceramic flame support layer); only combustion products mired with the atmosphere were detected at higher rates. Radiosity increased with increasing flow rate via increasing surface temperatures, while burner efficiencies decreased because of less effectual heat transfer of combustion product gases to solid surfaces. Stainless steel screen-based flame support layers demonstrated optimum performance as compared to ceramic and metal tube-based and reticulated ceramic-based flame support layers. increased turbulent flow and surface area for convective heat transfer between the base surface and the end of the flame support layer were factors attributed to improved burner radiosity and efficiency. The graybody temperatures and emittances of burners were determined using a simplex algorithm fit of spectral radiosity data to Planck's equation. The significantly higher and more gray emittance (hence radiosity) of CoAl2O4-coated mullite flame support tubes, as compared to alumina tubes of identical geometry, was demonstrated using this method.