Wolio is an Austronesian language spoken in and around Baubau on Buton Island, Southeast Sulawesi, Indonesia. It belongs to the Wotu–Wolio branch of the Celebic subgroup. Also known as Buton, it is a trade language and the former court language of the Sultan at Baubau. Today it is an official regional language; street signs are written in the Buri Wolio alphabet, based on the Arabic script.
Wolio has lexical borrowings from Malay, Arabic, and Dutch. Local languages of eastern Indonesia, such as Bugis, Makasar, and Ternate, have also been influential. The name "Buton", which also refers generically to various ethnic and linguistic groups of the Buton area, is said to be of Ternatese origin (butu, ‘market; marketplace’).