Po2, pO2, , 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