At Hus's suggestion Jerome sailed to England and studied at Oxford, Wycliffe's old seat of learning. For the next several years, Jerome moved about a good deal, spreading reform doctrines in Paris, Jerusalem, Heidelberg, Vienna, Russia, Lithuania, Hungary and Cologne. In his native Bohemia he sided with nationalistic students. He denounced a bull proclaiming an indulgence for a crusade against Naples.
When Hus was arrested by the Council of Constance, Jerome secretly followed, hoping to defend his friend. He discovered he could do nothing but was in great danger himself, and so he went to neighboring Idelberg and asked for safe conduct. Unwilling to do nothing, he had placards posted throughout Constance saying he was willing to appear before the bishops, that his character had been maligned, and that he would retract any error which could be proven against him. All he asked was a pledge of security.
When no pledge was forthcoming, Jerome headed home. On the way he was seized and sent in irons to the Council. A long chain was attached to the irons, and by this he was dragged into the cloister to be insulted, and then locked in a tower. His legs were fastened in stocks. For many days he was kept in this miserable condition. After Hus was burned, Jerome was threatened with torments if he would not recant. In a moment of weakness, he yielded.
Despite his recantation, he was not released. On the contrary, a second recantation was demanded. He said he would recant only in public. By then he had been a prisoner almost a year. At the public "recantation," he took back his earlier recantation and demanded a hearing to plead his cause. The Council refused this plea. Indignantly he protested, "To my enemies you have allowed the fullest scope of accusation: to me you deny the least opportunity of defense. . . ."
Jerome insisted he protested only against the bad behavior of the clergy. Unlike Hus he did not reject the doctrine of transubstantiation. Nonetheless, he was condemned to die in the flames as Hus had. For two days the council kept him in suspense, hoping to frighten him into a recantation. The Cardinal of Florence personally reasoned with him. Jerome remained steadfast. When a cap was made for him painted with red devils, he said, "Our Lord Jesus Christ, when he suffered death for me, a most miserable sinner, did wear a crown of thorns upon his head; and I for his sake will wear this adorning of derision and blasphemy. He sang hymns on his way to execution. Because of his vigor and health he was a long time dying in the flames. On this day, May 30, 1416, he and his paper crown were burned.
- Foxe, John. The New Foxe's Book of Martyrs. Rewritten and updated by Harold J. Chadwick. Gainesville, Florida: Bridge-Logos, 2001.
- "Jerome of Prague." New Schaff-Herzog Encyclopedia of Religious Knowledge. Grand Rapids: Baker Book House, 1954.
- "Jerome of Prague." The Oxford Dictionary of the Christian Church. Edited by F. L. Cross and E. A. Livingstone. Oxford: Oxford University Press, 1997.
- Spinka, Matthew. John Hus and the Czech Reform. Hamden, Connecticutt: Archon Books, 1966, 1941.