He published papers, chiefly in the Monthly Repository between 1818 and 1822, on such subjects as Faustus Socinus and Francis David, including The Italian Reformation, Memoirs of the Socini.
He started in the bookselling business, but on the advice of Abraham Rees (no relation), he was educated for the ministry (1799–1801) at Carmarthen College.
[2] In 1853 Rees left England for Spain, being unable to meet charges in regard to trust funds; but ultimately he made full restitution.
His intention, announced by 1833, of publishing a comprehensive work, was never fulfilled; the Antitrinitarian Biography by Robert Wallace appeared in 1850.
Rees published, besides single sermons (1804–46):[2] His historical papers included:[2] Rees left in manuscript The Anti-papal Reformers of Italy in the Sixteenth Century, with a Glance at their Forerunners, the Sectaries of the Middle Ages, in six volumes; also a manuscript translation, with notes, of Orelli's Life of Lælius Socinus.