Johan Afzelius (1753, Larv – 1837) was a Swedish chemist and notable as the doctoral advisor of one of the founders of modern chemistry, Jöns Jacob Berzelius.
Afzelius received his Master of Science degree at Uppsala University in 1776 under Torbern Olof Bergman.
Afzelius did mineral analyses (e.g., barium selenite). He is notable for having isolated formic acid from ants and showing formic acid was different from the closely related carboxylic acid, acetic acid. He also studied the chemistry of nickel and oxalic acid.
In 1801, he was elected a member of the Royal Swedish Academy of Sciences.