Where to find Zoltan Chivay?

I remember that I've also found him in the room where Vivaldi (the long bearded dwarf) stayed. He seems to wander between that area and the inn.

The wiki confirms:

Later in the game, Zoltan can be found wandering around the Temple Quarter (roughly from 8:00 a.m. to 8:00 p.m.) and, if choosing to side with the Scoia'tael or take the neutral path, in the Old Vizima. He also often spends time with Golan Vivaldi.

Found him at Vivaldi's place at 10:30 am.