The intention was to arrange a marriage between the young king and Grand Duchess Alexandra Pavlovna, a granddaughter of Catherine the Great.

However, the whole arrangement foundered on Gustav Adolf's unwavering refusal to allow his intended bride liberty of worship according to the rites of the Russian Orthodox Church.

On the contrary, when he came of age that year, thereby ending the regency, there were many who prematurely congratulated themselves on the fact that Sweden had now no disturbing genius, but an economical, God-fearing, commonplace monarch.

On 31 October 1797, Gustav married Friederike Dorothea, granddaughter of Karl Friedrich, Margrave of Baden, a marriage which seemed to threaten war with Russia but for the fanatical hatred of the French republic shared by the Emperor Paul of Russia and Gustav IV Adolf, which served as a bond between them.

Indeed, the king's horror of Jacobinism was intense, and drove him to become increasingly committed to the survival of Europe, to the point where he postponed his coronation for some years, so as to avoid calling together a diet.

Nonetheless, the disorder of the state finances, largely inherited from Gustav III's war against Russia, as well as widespread crop failures in 1798 and 1799, compelled him to summon the estates to Norrköping in March 1800 and on 3 April the same year.

On 5 June, Gustav Adolf's uncle was proclaimed King Charles XIII, after accepting a new liberal constitution, which was ratified by the diet the next day.

In exile Gustav Adolf used several titles, including Count Gottorp and Duke of Holstein-Eutin, and finally settled at St. Gallen in Switzerland where he lived in a small hotel in great loneliness and indigence,[3] under the name of Colonel Gustafsson.

At the suggestion of King Oscar II and Norway, his body was finally brought to Sweden and interred in Riddarholm Church.