Kallmann was born in Berlin in a jewish family. He studied at the University of Göttingen and wrote his dissertation under Max Planck, completing it in 1920. After which he worked at the Kaiser Wilhelm Institute for Physical Chemistry and Elektrochemistry. As a post-doctoral student he worked with Fritz Haber and Fritz London. In 1933 he was dismissed for Haber's institute due to his non-Aryan jewish descent. The companies IG Farben and AEG provided him a research lab to continue his work but with some restrictions. He survived thanks to his wife, who was not jewish and from a good family. His children were not considered as jewish by the nazi authorities. 
Kallmann built the world's first organic scintillator in Berlin.
In 1948, Kallmann's knowledge about photomultiplier scintillation counters brought him to the United States as a research fellow for the U.S. Army Signal Corps Laboratory in Belmar, NJ.
The modern day corporation, Thermo Electron, credits Kallmann and Broser at the Wayback Machine (archived October 15, 2003) with pioneering modern day scintillation counting by combining a scintillating material with a photomultiplier, as a means of improving light detection and reducing the eye fatigue apparently common to earlier, cruder methods of detection.
See the journal article in the Journal of Radioanalytical and Nuclear Chemistry, 'Scintillation of Organic Compounds Discovered by H. Kallmann, L. Herforth and I. Broser' 
Kallman worked for the US Signal Corps Engineering Laboratories, Fort Monmouth, New Jersey
Patent for Scintillator Solution Enhancers as found by Google 
The book, 'Pions to Quarks: Particle Physics in the 1950s' is referenced in this Google excerpt describing Kallmann's contribution to particle physics.
The Basic Process Occurring in Liquid Scintillation, as presented by Kallmann and Furst in 1957.
- "Tribute to Hartmut Kallmann". IEEE Transactions on Nuclear Science. 27 (1): 13. 1980. Bibcode:1980ITNS...27...13.. doi:10.1109/TNS.1980.4330792.
- "Fritz Habers "Chef des Stabes" Hartmut Kallmann – 1933 entlassen, 1948 emigriert". Retrieved 2009-05-07.
- Benjamin Bederson, "Fritz Reiche and the Emergency Committee in Aid of Displaced Foreign Scholars", Physics in perspective 7 p.453-472, 2005, p.459
- Niese, S. (2001). "Scintillation of Organic Compounds Discovered by H. Kallmann, L. Herforth and I. Broser". Journal of Radioanalytical and Nuclear Chemistry. 250 (3): 581. doi:10.1023/A:1017967021388.
- "Archived copy". Archived from the original on 2015-12-19. Retrieved 2012-11-15.CS1 maint: archived copy as title (link)
- "Scintillator solution enhancers".
- Brown, Laurie Mark; Dresden, Max; Hoddeson, Lillian (2009-01-29). Pions to Quarks: Particle Physics in the 1950s. ISBN 9780521100731.
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