COI may refer to:
Organizations
- Center on Organizational Innovation, a research center at Columbia University
- Central Office of Information, a former UK Government department
- Commission de l'Océan Indien, or Indian Ocean Commission
Science and technology
- California Oregon Intertie or Path 66, an electrical power transmission system
- Community of inquiry, a concept describing the social quality of scientific inquiry
- Community of interest (computer security), a computer networking technique of segregation of resources
- Confirmed opt-in, a policy for obtaining mailing list recipients
- Contingency Orbit Insertion, an abort mode of the Apollo spacecraft
- Cytochrome Oxidase Subunit 1, a gene
Art
- Center of Interest (COI), a focal point in a painting or other composition