Oxidative phosphorylation is used by living cells to generate ATP.

The process of oxidative phosphorylation involves the addition of a phosphate group using oxygen. This process occurs over a complex metabolic pathway involving multiple enzymes and paired reactions.

In most aerobic organisms, including eukaryotes and most prokaryotes, oxygen is used to obtain energy stored in the electron carriers NADH and FADH2 via the electron transport chain. This reaction occurs in the inner mitochondrial membrane, and it is used to generate 90 percent of the ATP made during glucose catabolism. This is why the mitochondria is considered the "power plant" of the cell.

Oxidative phosphorylation is dependent on a complex process called chemiosmosis and an enzyme called ATP synthase.