Karl-Hermann Geib (1908 – 1949) was a German physical chemist, who is co-author of a widely used industrial method for heavy water producing by isotopic exchange between H2S and H2O (the Geib–Spevack (GS) process or Girdler sulfide process).
In 1931, Karl-Hermann Geib graduated Leipzig University and joined the Kaiser-Wilhelm Institut für physikalische Chemie und Elektrochemie of the Kaiser-Wilhelm Gesellschaft in Berlin-Dahlem. The first scientific work he performed under the direction of Paul Harteck. Shortly after Hartek highway crossing in Cambridge Geib returned to alma mater - the Leipzig University and married Hedwig Delbruck. He began exploring the reactions of the newly opened deuterium. Independently and jointly with V. T. Forster, E. W. R. Steacie, A. Lendl, R. K. F. Bonhoeffer and L. D. C. Bok he published a number of papers, the results of which are reflected in his review.In 1937, Geib defended his doctoral thesis.
After beginning of World War II (1940), Geib went to the chemical industrial complexes Leunawerke and proceeded under the Hartek's direction of the development process production of heavy water by a two-temperature isotopic exchange between hydrogen sulfide and water. So he received reservation on the mobilization, which for him was a significant factor.
The developed process was more effective than process with exchange in a hydrogen-water system, but its implementation was delayed. To create production capacity due to corrosion of hydrogen sulfide would take a lot of special alloys, which in time of war there is a shortage. Simultaneously developed by Jerome Spevak in the U.S. (1943) the same process did not develop at first for the same reason.Immediately after the war under the auspices of the Soviet Military Administration in Germany and other agencies in the Leunawerke had assembled a group of experts, led by Paul Herold, a former Director on science. Geib joined the group. Pilot plants were restored and study of the process by isotopic exchange between hydrogen and water was continued. Besides the preliminary draft of plant with hydrogen sulfide annual capacity 5 tons of heavy water was designed.