Never before has an optical method been used to determine the arc temperature inside a submerged arc welding cavern with frequencies up to 5 kHz. To be able to do that, a combination of high-speed imaging and spatially resolved high-speed spectroscopy with up to 5000 fps has been performed. A DCEP (direct current electrode positive) process with 600, 800, 900 and 1000 A, and an AC (alternating current) process at 800 A were included in this research. The Bartels method has been used to calculate these temperatures for the first time. It generated temperatures from approximately 7000–9000 K. Also, it was found that a decrease of arc temperature for rising currents appeared until 900 A. After that, it is reversed for currents higher than 900 A.