H Harn
H Height
HACD Home Area Customer Dialing
HAL Heuristically programmed ALgorithmic computer (filme 2001)
HAM Hold And Modify
HAO High Altitude Observatory (Espacial)
Hb HemogloBin
HBM Her British Majesty; His British Majesty
HBO Home Box Office
HC Holy Communion
HC House of Commons
HCFA Health Care Financing Administration
HCFC hydrochlorofluorocarbon (Química)
HCL High Cost of Living
HD Hard Disk
HD Heavy Duty
HD Henry Draper catalog entry (Espacial)
HDA Head Disk Assembly (em discos rígidos)
HDBV Host Data Base View
HDL High Density Lipoprotein
HDLC High-level Data Link Control (Networking)
HDTV High Definition Television
HE His Eminence
HE His Excellency
HEAO High Energy Astronomical Observatory (Espacial)
HEDM High Energy-Density Matter (Espacial)
HEMP Help End Marijuana Prohibition
HEO High Earth Orbit (Espacial)
HEPnet High Energy Physics network (Networking)
HERO Hazards of Electromagnetic Radiation to Ordnance
HF High Fantasy
HF High Frequency (3-30MHz)
HFE Human Factors Engineering
HFS Hierarchical File System
HGA High Gain Antenna (Espacial)
HHS Health and Human Services (Departamento americano)
HI Hawaii
HIIPS Hud Integrated Information Processing Services
HLC Heavy Lift Capability (Espacial)
HLL High-Level Language
HLV Heavy Lift Vehicle (Espacial)
HMC Halley Multicolor Camera (em Giotto) (Espacial)
HMOS High performance Metal Oxide Semiconductor (veja também MOS)
HMS His/Her Majesty's Ship
HMT His/Her Majesty's Transport
HNPA Home Numbering Plan Area (Telefonia)
HOBIS HOtel Billing Information System 
HOL High-Order System
HOTOL HOrizontal Take-Off and Landing
HP Hewlett Packard, Inc. (nome de companhia)
HP High Pressure
HP Higher Power (usualmente Deus)
HP Hit Points
HP HorsePower
HPGe High Purity Germanium
HPL/T High-Productivity Languages/Tools
HQ HeadQuarters
HR Hertzsprung-Russell (diagrama) (Espacial)
HR House of Representatives
HRH Her Royal Highness
HRH His Royal Highness
HRI High Resolution Imager (em ROSAT) (Espacial)
HS High School
HSB Hue, Saturation, Brightness
HSP High Speed Photometer (em HST) (Espacial)
HST Hawaiian Standard Time
HST Hubble Space Telescope (Espacial)
HT High Tension (como em transmissão de força elétrica)
HTK Hits To Kill
HUAC House Unamerican Activities Committee
HUD Heads Up Display
HUD Housing and Urban Development (Governo americano)
HUPD Harvard University Police Department
HUT Hopkins Ultraviolet Telescope (Espacial)
HV High Voltage
HVAC Heating, Ventilation, and Air Conditioning
HW2000 Highway 2000
HWM High-Water Mark
Hz HertZ (unidade de freqüência, ciclos por segundo)
® Pesquisa RXA