Askio (Greek: Άσκιο) is a former municipality in Kozani regional unit, West Macedonia, Greece. Since the 2011 local government reform it is part of the municipality Voio, of which it is a municipal unit. The 2011 census recorde 4,002 residents in Askio. The seat of the municipality was in Kaloneri. It was named after the Askio mountain range which covers most of the municipal unit.