H3

H3, H03 or H-3 may refer to:

* "H3" (film), a 2001 film about the 1981 Irish hunger strike
* H3 Monks Way, a road part of the Milton Keynes grid road system
* H3 Pharmaceutical Chemistry, a higher paper for GCE 'A' level chemistry for Singapore students
* H3 (pyrotechnics), a pyrotechnic composition
* H-3 Sea King, a United States Navy helicopter
* ATC code H03, a section of the Anatomical Therapeutic Chemical Classification System
* British NVC community H3, a heath community of the British National Vegetation Classification system
* DSC-H3, a 2008 Sony Cyber-shot H series camera
* Highway H03 (Ukraine), a
* Histamine H3 receptor, a human gene
* Histone H3, a component of DNA higher structure in eukaryotic cells
* HMS Grenville (H03), a 1935 British Royal Navy destroyer
* HMS H3, a 1915 British Royal Navy H class submarine
* Hummer H3, the smallest of the three Hummer models sold by General Motors
* Interstate H-3, a highway in Hawaii
* PRR H3, an American
* Standard H-3, an improved version of the 1916 Standard H-2 aircraft
* USS H-3 (SS-30), a 1914 United States Navy H-class submarine

and also :
* Disorders of eyelid in diseases classified elsewhere code
* Hash House Harriers, an international social, non-competitive running, social, and drinking clubs
* H3 or Harrison Number Three, an 18th century marine chronometer
* "Happy Hustle High", a manga series by Rie Takada
* "Halo 3", a video game by Bungie Studios for the Xbox 360
* Hydrogen-3, H-3, ³H (a.k.a. Tritium), an unstable isotope of Hydrogen
* The trihydrogen cation, H₃⁺, one of the simplest polyatomic molecules