H4, H04, or H-4 may refer to:
Science and mathematics ATC code H04 Pancreatic hormones, a subgroup of the Anatomical Therapeutic Chemical Classification System Histamine H4 receptor, a human gene Histone H4, a protein involved in the structure of chromatin in eukaryotic cells Hydrogen-4 (H-4), an isotope of hydrogen H4, a symmetry group in the fifth dimension; see H4 polytope H-4, a huge eruption of the Hekla volcano around 2310 BC
Technology H-4 SOW, a precision-guided glide bomb used by the Pakistan Air Force H4 (chronometer), an 18th-century marine chronometer designed by John Harrison Zoom H4 Handy Recorder, a handheld digital audio recorder , level 4 heading markup for HTML Web pages, see HTML element#heading
Transport Automobiles and roads H4, a halogen headlamp bulb H4, development name of the Hummer HX concept car H-4, shorthand for a 4-cylinder horizontally opposed or "flat four" engine H4 Dansteed Way, a road in Milton Keynes, England
Aviation GEN H-4, a Japanese helicopter design Hughes H-4 Hercules (Spruce Goose), the largest flying boat ever built Héli Sécurité Helicopter Airlines (IATA code), based in France; see List of airline codes (H) Inter Islands Airlines (IATA code), a former airline based in Cape Verde
Ships and submarines HMS H4, a 1915 British Royal Navy H-class submarine HMS Tenedos (H04), a 1918 British Royal Navy Admiralty S-class destroyer USS H-4 (SS-147), a 1918 United States Navy submarine
Rail GNR Class H4, a class of British steam locomotives
Other uses Halo 4, a video game created by 343 Industries for the Xbox 360 H4 (film), a 2013 film H-4 visa, issued by the U.S. Citizenship and Immigration Services British NVC community H4, a heath community in the British National Vegetation Classification system H4 (classification), a cycling classification used in para-cycling
See also
4H (disambiguation)
HHhH, a novel by the French author Laurent Binet