| H | Hydrogen |
| Ha | Hahnium |
| HAC | Hands-free Add on Circuit |
| HAP | Hazardous Air Pollutant |
| HARM | High-speed Anti-Radar Missile |
| HASL | Hot Air Solder Leveling |
| HAST | Highly Accelerated Stress Testing |
| HAZCOM | Hazard Communication Standard |
| HB | Horizontal Bridgman (crystal) |
| HBT | Heterojunction Bipolar Transistor |
| HCI | Hot Carrier Injection |
| HCMOS | High-density Complementary Metal-Oxide Semiconductor |
| HCP | Hexagonal Close Packed |
| HCS | Hot-Carrier Suppressed |
| HCT | High-speed CMOS TTL compatible |
| HD | High Density; High Definition |
| HDCP | High Bandwidth Digital Content Protocol |
| HDL | Hardware Description Language |
| HDP | High Density Plasma; Hydrostatic Deformation Potential |
| HDPE | High-Density PolyEthylene |
| HDSD | Hydrogen Defect Shallow Donors |
| HDSL | High (bit rate) Digital Subscriber Line |
| HDTV | High Definition TV |
| He | Helium |
| hecto | 1.00E+2 (100/1; symbolized by the prefix h) |
| HEM | Hydrogenic Effective Mass |
| HEMT | High Electron Mobility Transistor |
| HEPA | High-Efficiency Particulate Air |
| Hf | Hafnium |
| HF | Hydrofluoric acid; High Frequency |
| HFC | Hybrid Fiber/Coax |
| HFET | Heterojunction FET |
| HFI | HyperFine Interaction |
| HFRR | HydroFluoric acid Reprocessor Return system |
| HFS | HyperFine Shift |
| Hg | Mercury |
| HGF | Horizontal Gradient Freeze |
| HGL | Hewlett-Packard Graphics Language image format |
| HIBS | Heavy Ion Backscattering Spectrometry |
| HIC | Hybrid Integrated Circuits |
| HIGFET | Heterojunction Insulated Gate FET |
| HIPOX | HIgh-Pressure OXygen |
| HIPPI | High Performance Parallel Interface |
| HITS | Head-End-in-the-Sky (AT&T) |
| HLF | Horizontal Laminar Flow |
| HMAC | Keyed-Hash Message Authentication Code |
| HMDS | HexaMethylDiSilazane |
| HMIS | Hazardous Materials Inventory Statement |
| HMMP | Hazardous Materials Management Plan |
| HMOS | High-performance MOS; High-density MOS |
| Ho | Holmium |
| HOLZ | Higher-Order Laue Zone |
| HOMER | Hazardous Organic Mass Emission Rate |
| HOMO | Highest Occupied Molecular Orbital |
| HOPG | Highly-Oriented Pyrolitic Graphite |
| HP | High Purity |
| HPC | High Performance (micro) Controller |
