Abstract: Compacts of α-Al₂O₃ and Mo powder were heated in radio-frequency (RF) induced low pressure N₂, H₂, Ar, and their mixture plasma. An optical pyrometer, a radiation pyrometer, and a system called Accufiber Model 310 were used to measure the temperature of compacts heated in the plasma. The results indicate that there are different heat transfer mechanisms from plasma to specimens of different physical properties. The Ar plasma showed the highest heating ability among N₂, H₂, and Ar plasma for Al₂O₃ specimens, whereas the H₂ plasma could heat Mo specimens to a higher temperature than the Ar plasma did, even under the same generating conditions.