HCA
- Brilliant (diamond cut)
- HCA (classification)
- Hall–Carpenter Archives
- Hans Christian Andersen
- Healthcare Assistant
- Heidelberg Center for American Studies
- Helsinki Citizens' Assembly
- Hennepin Center for the Arts
- Heritage Christian Academy (Fort Collins, Colorado)
- Heritage Christian Academy (Kansas)
- Heritage Christian Academy (Minnesota)
- Heritage Christian Academy (New Jersey)
- Heritage Christian Academy (Texas)
- Heritage Christian Academy (disambiguation)
- Heritage Crafts Association
- Heterocyclic amine
- Hexachloroacetone
- Hierarchical cluster analysis
- High Court of Australia
- High content analysis
- Hillcrest Christian Academy
- Historical cost accounting
- Hollywood Critics Association
- Holy Child Academy
- Homes and Communities Agency
- Hopkins Consulting Agency
- Hospital Corporation of America
- Host channel adapter
- Hydaburg Cooperative Association
- Hydroxycitric acid