In Missolonghi he cooperated with Alexandros Mavrokordatos and was set in several gubernatorial positions (secretary of executive) in the Provisional Administration of Greece. He took part in the First Greek National Assembly at Epidaurus. There, almost on his own, he wrote the new state's constitution and the declaration of 15 January 1822, which informed the European powers, allied in the Holy Alliance, that the revolution was national and not social. In 1823 he was in charge of the committee, which was sent to London for the negotiation of a public loan. In 1827, he was elected representative to the National Convention at Troezen. In October of the same year, he went to Paris, in order to continue his studies.