H0 (H followed by zero) or H00 may refer to:
- H0 scale, used in rail transport modelling
- Higgs boson, in physics, symbol H<sup>0</sup>
- Hammett acidity function, in chemistry, H<sub>0</sub>
- Hubble constant, in cosmology, H<sub>0</sub>
- Null hypothesis, in statistics, often denoted H<sub>0</sub>
- , a British and later Canadian warship
- Stye, a bacterial infection of the eyelid, ICD-10 code H00
See also