[1][2] Jan II took the full government over Oświęcim after his father's death on 29 September 1372.

During almost all his rule, Jan II had considerable financial difficulties, because he was committed to repay the sum illegally obtained by his father from the Scholastic of Kraków.

His wife was mentioned as a widow in document of his father-in-law Ludwik I the Fair from 8 September 1376.

In the anniversary of the St. Jadwiga Collegiate Church in Brzeg there is mention about Jan, duke of Oświęcim, died on 19 February.

[1] By 1366, Jan II married with Jadwiga (c. 1344–1351 – 30 January 1386 or 1396), daughter of Ludwik I the Fair, Duke of Brzeg.