COO may refer to:
- Country of origin
- Certificate of origin, used in international trade
- Chief operating officer or chief operations officer, high ranking corporate official
- Cell of origin (telecommunications)
- Carboxylate, type of anion
- Cobalt(II) oxide, chemical with formula of CoO.
- Cadjehoun Airport (IATA Code: COO), in Cotonou, Benin
- Calgary Olympic Oval, Canadian ice rink
- coo, the call of pigeons
- Summer Days with Coo, a 2007 Japanese animated film
- CoO Cost of Ownership