The goal of this thesis is to develop a set of standards for use in calibrating heat flux gages at elevated temperatures in a radiant heat transfer environment by comparing several "trial" standards. Ideally, the same incident heat flux is derived from each standard when exposed to the same heat source. Three heat flux standards are proposed and evaluated. The standards are based on temperature measurements, material properties, and electrical measurements. The theory and design of each standard are described, as are the calibration procedures used. For experimental comparisons, two standards are simultaneously exposed to heat fluxes of up to 220 W/cm² by placing one standard on each side of a graphite flat plate heater. The temperature measurement based standard derives incident heat flux from the temperature of a blackbody heat source and the Stefan-Boltzmann law. The heat flux gage employed in this standard is a water-cooled Gardon gage. This standard does not operate at high temperatures. The calibration of this standard produced highly repeatable results. / Master of Science