OCI may refer to:
Businesses and organizations OCI (company), green energy and chemical company, South Korea Oakwood Collegiate Institute, Toronto, Canada Office of Criminal Investigations of the U.S. Food and Drug Administration Olympic Council of Ireland, former name the national olympic committee of Ireland Ontario Cancer Institute, Canada Order of the Crown of Italy, Italian order Open Constitution Initiative, advocacy group in China OCI NV, parent company of Orascom Construction Ottawa Collegiate Institute, now Lisgar Collegiate Institute, Canada Organisation Communiste Internationaliste, (Internationalist Communist Organisation), former French political party
Computing Open Catalog Interface, an interface standard in computing Open Container Initiative, a Linux standards project in computing Oracle Call Interface, database interface software
Other uses oci, ISO 639-2/3 language code for Occitan language Organizational conflict of interest Other comprehensive income Overseas Citizen of India, a scheme granting a status similar to, but not the same as, dual citizenship in India