Placzek was born in Brno, Moravia, then part of Austria-Hungary, into a wealthy Jewish family. He studied physics in Prague and Vienna. In the 1930s, Placzek was known as an adventurous person with sharp sense of humor, a tireless generator of novel physics ideas which he generously shared with his colleagues. The scope of Placzek's pilgrimage around world's physics centers in the 1930s was unique among his colleagues. He worked with Hans Bethe, Edward Teller, Rudolf Peierls, Werner Heisenberg, Victor Weisskopf, Enrico Fermi, Niels Bohr, Lev Landau, Edoardo Amaldi, Emilio Segrè, Otto Frisch, Leon van Hove and many other prominent physicists of his time. His wife, Els Placzek (née Andriesse) was an ex-wife of physicist Hans von Halban. He lost all his relatives to Holocaust, casting a tragic shadow on his life. 
Placzek's major areas of scientific work involved a fundamental theory of Raman scattering, molecular spectroscopy in gases and liquids, neutron physics and mathematical physics. Together with Otto Frisch, he suggested a direct experimental proof of nuclear fission. Together with Niels Bohr and others, he was instrumental in clarifying the role of Uranium 235 for the possibility of nuclear chain reaction.
During his stay in Landau's circle in Kharkiv around 1937, Placzek witnessed the brutal reality of Joseph Stalin's regime. His first-hand experience of this influenced the political opinions of his close friends, in particular, fathers of nuclear and thermonuclear bombs, Robert Oppenheimer and Edward Teller. 
Later, Placzek was the only Czech with a leading position in the Manhattan project, where he worked from 1943 till 1946 as a member of the British Mission; first in Canada as the leader of a theoretical division at the Montreal Laboratory and then (since May 1945) in Los Alamos, later replacing his friend Hans Bethe as the leader of the theoretical group. Since 1948, Placzek was a member of the Institute for Advanced Study in Princeton, USA.
Unlike many trailblazers of nuclear physics, George Placzek did not leave his recollections or life story notes. Many new facts about Placzek's life and his family roots emerged in connection with a Symposium held in Placzek's memory. Placzek's premature death in a hotel in Zurich was very likely a suicide influenced by his long-time serious illness.  The first detailed biography of George Placzek  sheds light on poorly known pages of his life, illuminating also circumstances of Placzek's death.
|Wikimedia Commons has media related to Georg Placzek (physicist).|
- J. Fischer: George Placzek - an unsung hero of physicsCern Courier, Vol. 45, No. 7, 2005.
- A. Gottvald: Kdo byl Georg Placzek (1905-1955) Archived 2007-06-25 at the Wayback Machine. Čs. čas. fyz., Vol. 55, No. 3, 2005, pp. 275-287 (in Czech) (pdf)
- Gottvald, Aleš; Shifman, Mikhail (2018). George Placzek - A Nuclear Physicist's Odyssey. Singapore: World Scientific. ISBN 978-981-3236-91-2.
- Frisch O. R.: "The Discovery of Fission – How It All Began". Physics Today 20 (1967), 11, pp. 43-48
- Wheeler J. A.: "Mechanism of Fission". Physics Today 20 (1967), 11, pp. 49-52
- D. C. Fakley: "The British Mission". Los Alamos Science, Winter/Spring 1983, pp. 186-189
- Abstracts from the Symposion in Memory of George Placzek (1905-1955), Brno (Czech Republic), 2005