Nyitra County
It is plausible that John attended the University of Bologna, where obtained a degree of doctor of canon law (). He was styled as "magister" throughout his ecclesiastical career. When he returned to Hungary, his ecclesiastical career ascended quickly into the highest dignities. He functioned as a royal chaplain in the court of Stephen V from 1270 to 1272. He retained his position following the ascension of Ladislaus IV to the Hungarian throne. Beside his office in the royal court, John also served as archdeacon of Gömör in the Archdiocese of Esztergom between 1273 and 1274. He was granted the villages Újlak and Özdöge (present-day Veľké Zálužie and Mojzesovo in Slovakia, respectively) for his faithful service by Ladislaus IV in October 1273. The young monarch also donated a land called Harsány in Nyitra County to John for the same reason in July 1274.