H2
H2, H02, or H-2 may refer to:
Roads and transportation
Interstate H-2, a highway in Hawaii, located on the island of Oahu
London Buses route H2
Science
H2, the chemical formula for hydrogen gas
Hydrogen-2, H-2, 2H (called deuterium), the isotope of hydrogen with one proton, one neutron, and one electron
Dihydrogen, or H2, molecular hydrogen composed of two hydrogen atoms
H II region
ATC code H02 Corticosteroids for systemic use, a subgroup of the Anatomical Therapeutic Chemical Classification System
Histamine H2 receptor
Prostaglandin H2
H-2, the Major histocompatibility complex of the mouse (equivalent of the Human Leukocyte Antigens)
*h₂, one of the three laryngeals in the reconstructed Proto-Indo-European language
or 
, wide- or narrow-sense heritability
<h2></h2>, level 2 heading markup for HTML Web pages, see HTML element#heading
Vehicles
H-II, a family of Japanese liquid-fueled rockets
H-IIA
