COO or coo may refer to:

• Certificate of origin, used in international trade
• Chief operating officer or chief operations officer, high-ranking corporate official
• Concept of operations, used in Systems Engineering Management Process
• Country of origin, a representative to the country or countries of manufacture, production, design, or brand origin where an article or product comes from

• Cell of origin (telecommunications)
• "Coo", the call of pigeons and doves

• Coo Coo Cal (Calvin Bellamy, born 1970), American rapper
• Coo Coo Marlin (1932–2005), racing driver
• Clara Oswin Oswald, fictional character

• Carboxylate, type of anion
• Cobalt(II) oxide, chemical with formula of CoO

• Coo, the former Italian name for the Dodecanese island Kos, now in Greece, off the coast of Turkey
• Calgary Olympic Oval, a Canadian ice rink
• COO, the IATA code for Cadjehoun Airport in Cotonou, Benin
• COO, the National Rail code for Cookham railway station in the county of Berkshire, UK

• Daihatsu Coo, a 2006–2012 Japanese subcompact hatchback
• Summer Days with Coo, a 2007 Japanese animated film
• The Cooper Companies, a medical device company which trades on the NYSE as COO
• Coo - A Scotticism for cow

• All pages with titles containing COO
• All pages with titles beginning with COO