HHT can be an abbreviation for
- Handheld terminal
- Headquarters and Headquarters Troop in the U.S. Army
- Heinrich Hertz Telescope on Mount Graham
- Hereditary hemorrhagic telangiectasia or Rendu-Osler-Weber disease
- Hilbert–Huang transform (mathematics)
- Historic House Trust of New York City
- Historic Houses Trust, New South Wales — state government trust in Australia