H1

H1, H-1, H01, H I and their variations may refer to:

Science

• H1 (particle detector)
• H1, Histamine H1 receptor
• H1, Histone H1, a protein
• H1, British NVC community H1 heath zone
• H₁, hydrogen atom
• *h₁, one of the three laryngeals in the reconstructed Proto-Indo-European language
• <h1></h1>, level 1 heading markup for HTML Web pages, see HTML element#heading
• H I region

ATC code H01 Pituitary and hypothalamic hormones and analogues, a subgroup of the Anatomical Therapeutic Chemical Classification System statistical category of eyelid inflammations

• DSC-H1 camera
• Haplogroup H1, a grouping in genetics based on certain similarities

Statistics

• H₁, denotation for Alternative Hypothesis

Transportation

Aviation

• Bell H-1, two helicopters with that designation
• H1, Hooters Air airline
• Hughes H-1 Racer, a racing aircraft

Motor vehicles

• H1, Hummer H1 Humvee-like vehicle
• Hyundai H-1, group of car models

Roads

• H-1, Interstate H-1, a highway in Hawaii

Ships and maritime

• H1, John Harrison's first marine chronometer
• H1, H1 Unlimited, a premier unlimited hydroplane racing league
• HMS H1, a 1915 British Royal Navy H-class submarine
• HMS Hotspur (H01), a 1935 British Royal Navy H-class destroyer
• USS H-1, a 1913 United States Navy submarine

Trains and rail transport

• LB&SCR H1 class, locomotive
• LNER Class H1, locomotive
• Designation for METRORail Siemens S70 light rail vehicles

Others

• H1 Lamp, automotive halogen light bulb
• H-I rocket, a Japanese rocket
• H-1 (rocket engine)
• H1 Unlimited, a hydroplane racing league
• H-1 Heliac stellarator, now H-1NF

Others

• H-1B visa