Portal:History of science/Selected anniversaries/September 30
- 1550 - Birth of Michael Maestlin, German mathematician (d. 1631)
- 1870 - Birth of Jean Baptiste Perrin, French physicist, Nobel laureate (d. 1942)
- 1882 - The world's first commercial hydroelectric power plant (later known as Appleton Edison Light Company) begins operation on the Fox River in Appleton, Wisconsin, United States
- 1905 - Birth of Nevill Francis Mott, English physicist, Nobel Prize laureate (d. 1996)
- 1939 - Birth of Jean-Marie Lehn, French chemist, Nobel Prize laureate
- 1943 - Birth of Johann Deisenhofer, German chemist, Nobel Prize laureate
- 1994 - Death of Andre Michael Lwoff, French microbiologist, Nobel laureate (b. 1902)
- 2004 - The first images of a live giant squid in its natural habitat are taken 600 miles south of Tokyo