Gadolin was fluent in Latin, Finnish, Russian, German, English and French in addition to his native  Swedish. He was a candidate for the chair of chemistry at Uppsala in 1784, but Johann Afzelius was selected instead.  Gadolin became an extraordinary professor at Åbo in 1785 (an unpaid position). Beginning in 1786, he made a chemical "grand tour" of Europe, visiting universities and mines in various countries.  He worked with Lorenz Crell, editor of the journal Chemische Annalen in Germany, and with Adair Crawford and Richard Kirwan in Ireland.
Gadolin was elected a member of the Royal Swedish Academy of Sciences in 1790.
Gadolin became the ordinary professor of chemistry at the Royal Academy of Turku in 1797, after the death of Pehr Adrian Gadd.  He retained the position until his retirement in 1822. He was one of the first chemists who gave laboratory exercises to students. He even allowed the students to use his private laboratory.