Jędrzej Śniadecki (archaic English: Andrew Sniadecki; 30 November 1768 – 12 May 1838) was a Polishwriter, physician, chemist and biologist. His achievements include the creation of modern Polish terminology in the field of chemistry.
Śniadecki's most important book was Początki chemii (The Beginnings of Chemistry), the first Polish-language chemistry textbook, prepared for the Commission of National Education. It was considered one of the best Polish scientific textbooks of the age and was used in Polish universities well into the 1930s. Śniadecki was also known as a writer of less serious works; a co-founder of Towarzystwo Szubrawców (the Wastrel Society), he contributed articles to its satirical weekly, Wiadomości Brukowe (The Gutter News). He also wrote copiously in Wiadomości Wileńskie (The Vilnius' News), the largest and most prestigious daily in Vilnius.
Śniadecki may have been the original discoverer of the element ruthenium in 1807, thirty-seven years before Karl Klaus.