Oscar Kjellberg (21 September 1870 – 5 July 1931) was a Swedish inventor and industrialist. Founder of Elektriska Svetsnings-Aktiebolaget (ESAB), in 1904, and Kjellberg Finsterwalde, in 1922. He invented the coated electrode used in manual metal arc welding (Swedish Patent: 27152, June 29, 1907), by dipping a bare iron wire in a thick mixture of carbonates and silicates. The purpose of the coating is to protect the molten metal from oxygen and nitrogen present in the atmosphere. His pioneering of covered electrode development paved the road during the next twenty years in the research of reliable flux coated electrodes.