SO2 or SO<sub>2</sub> may refer to:
Science
- Sulfur dioxide (SO<sub>2</sub>), a colorless gas with a pungent smell
- Sulfonyl group (R-SO<sub>2</sub>-R), a functional group found primarily in sulfones, or a substituent
- SO(2), special orthogonal group of degree 2 in mathematics
- Oxygen saturation (SO<sub>2</sub>), the concentration of oxygen dissolved in a medium
- S2 (star) or S0–2, a star near the central black hole at the center of the Milky Way
- 2015 SO<sub>2</sub> or 2015 SO2, an Aten asteroid
Military and police
- SO2, a staff officer of the second class, often a commissioned officer of lieutenant commander, major or squadron leader rank
- SO2, a London Metropolitan Police Specialist Operations command division
- Special Operations 2 – Operational, of the British, World War II Special Operations Executive
Other uses
<!--* Star Ocean 2, a video game (fails WP:DABACRO)-->
- SO2 (album), a 2010 album by Shinichi Osawa
See also
- Oxygen saturation (medicine) (SaO<sub>2</sub>, SvO<sub>2</sub>, StO<sub>2</sub>, SpO<sub>2</sub>)
- Soso (disambiguation)
- Soo (disambiguation)
- SO (disambiguation)
