Josef Mattauch received his doctorate in Vienna in 1920 and worked for several years as an assistant at the III Institute of Physics. A Rockefeller scholarship enabled him to spend time in the USA. With Robert Andrews Millikan at the University of Chicago, he participated in mass spectroscopic studies. In Vienna, Mattauch established a laboratory for mass spectroscopy where, in collaboration with other researchers, he achieved a significant improvement in the sharpness and sensitivity of mass spectroscopic detection of isotopes.
As a result, Mattauch moved up to become one of the leading researchers in the field of accurate atomic weight determination. After Lise Meitner’s emigration, Mattauch became her successor at the Kaiser Wilhelm Institute for Chemistry and succeeded Otto Hahn as director of the institute in 1946. In 1952, he was able to use mass spectrography to continue precision determinations of isotope masses already begun during the war. This led to the exact measurement of the nuclear masses of the neutron, proton and chlorine.