"Cox1" redirects here. Particularly in a medical context, this can also refer to cyclooxygenase-1 (COX-1).

Cytochrome c oxidase I (COX1) also known as mitochondrially encoded cytochrome c oxidase I (MT-CO1) is a protein that in humans is encoded by the MT-CO1 gene. In other eukaryotes, the gene is called COX1, CO1, or COI. Cytochrome c oxidase I is the main subunit of the cytochrome c oxidase complex.