Po2, pO<sub>2</sub>, , or PO2 may refer to:
- A military rank:
- Petty Officer 2nd Class in the Canadian military
- Petty Officer Second Class in the United States military
- Polikarpov Po-2 or U-2, a Soviet aeroplane
- Partial pressure of Oxygen, that is, amount of oxygen in the blood <!-- --> (normally referred to as Dissolved Oxygen)
- : Phosphorus dioxide, a gaseous free radical that plays a role in the chemiluminescence of phosphorus and phosphine.
- : Polonide anion
- a power of two in mathematics