From 1518 he continued his studies at the University of Leipzig where he also worked as a tutor. He was the cantor of Leipzig Thomanerchor from 1518 to 1520. During Luther's Leipzig Debate, he performed his mass Missa de Sancto Spiritu for twelve voices on 27 June 1519.

In 1520 Rhau had to leave Leipzig, due to his favourable attitude towards the Reformation, and went on