| Acronym | Meaning |
| HMXB | High-mass X-ray Binaries |
| HNBR | Hydrogenated Acrylonitrile-butadiene Rubber |
| HNC | Hypernetted Chain |
| HNE | Human Neutrophil Elastase |
| HNF | Hepatocyte Nuclear Factor |
| HNFETB | Hybridization Of Nearly Free Elctrons With Tightly Bound States (for Band-structure Calcns.) |
| HNGF | Human Nerve Growth Factor |
| HNLC | High-nutrient Low-chlorophyll |
| HNN | Hybrid Neural Network |
| HNPCC | Hereditary Nonpolyposis Colorectal Carcinoma |
| HNS | Explosive |
| HNSCC | Head And Neck Squamous Cell Carcinoma |
| HOAT | 1-hydroxy-7-azabenzotriazole (peptide Coupling Agent) |
| HOC | Halogenated Organic Carbons |
| HOC | Hydrophobic Organic Compounds |
| HOCO | Highest Occupied Crystal Orbital |
| HOCS | Harmonic-oscillator Coherent States |
| HOE | Holographic Optical Element |
| HOEF | Harmonic Oscillator With External Field Model (in Collisions) |
| HOESY | Heteronuclear Overhauser Enhancement Spectroscopy |
| HOFF | Hybrid Orbital Force Field |
| HOHAHA | Homonuclear Hartman-Hahn Spectroscopy |
| HOLZ | Higher Order Laue Zone |
| HOMBA | Higher-order Modified Born Approxn. (in Potential Scattering) |
| HOMER | Hazardous Organic Mass Emission Rate |
| HOMO | Highest Occupied Molecular Orbital |
| HON | Hazardous Organic NESHAP |
| HOPC | High Osmotic Pressure Chromatography |
| HOPG | Highly Oriented Pyrolytic Graphite |
| HORSES | Higher-order Raman Spectral Excitation Studies |
| HOSE | Harmonic Oscillator Stabilization Energy |
| HPA | Hybridization Protection Assay |
| HPA | Hydroxypropyl Acrylate |
| HPAC | High Performance Affinity Chromatography |
| HPAE | High Performance Anion Exchange |
| HPAEC | High-performance Anion-exchange Chromatography |
| HPAM | Hydrolyzed Polyacrylamide |
| HPC | Heterotrophic Plate Count |
| HPCA | Hierarchical Principal Component Analysis |
| HPCCP | High Performance Computing And Communications Program |
| HPCE | High-performance Capillary Electrophoresis |
| HPCIC | High-performance Chelation Ion Chromatography |
| HPCN | High-Performance Computing And Networking |
| HPCPC | High Performance Centrifugal Partition Chromatography |
| HPCZE | High Performance Capillary Zone Electrophoresis |
| HPDM | Hybrid Plume Dispersion Model (air Quality) |
| HPDSC | High-pressure Differential Scanning Calorimetry |
| HPET | High Performance Engineering Thermoplastic |
| HPGE | High Purity Germanium |
| HPHF | Half-projected Hartree-Fock Model |