Not a fan of ostentation, he continued to wear his Benedictine habit. A fan of education, he restored a school of medicine in Montpelier. His personal physician was the most-renowned surgeon of the day. He tried to restore the papacy to Rome from Avignon. He tried to get England to pay several years' worth of payments due the papacy, and clashed with Wycliffe over it. He attempted a Crusade against the Turks, which never got off the ground.
He also took a strong stand against heretics.
In 1363, he proclaimed the papal bull In caena Domini (At the table of the Lord), a collection of pronunciations of popes that merited excommunication for transgressors, and for which only the pope could give absolution. This bull, amended to include later papal injunctions, was repeated annually on Holy Thursday or Easter Monday. It listed infringements against papal authority as well as heresies, sacrileges, and other crimes. It was used to justify many an inquisition.
Over the centuries, rulers of Europe—both Catholic and Protestant—considered In caena Domini to be an infringement on their rights as sovereigns and complained. The annual recital of it was finally ended in 1770 by Pope Clement XIV.