HCI
- HCIL (disambiguation)
- HCL (disambiguation)
- Handgun Control, Inc.
- Happy Computers
- Harbord Collegiate Institute
- Harrisburg City Islanders
- Heavy-Chemical Industry Drive
- Highly charged ion
- Home Computer Initiative
- Host controller interface (disambiguation)
- Hot carriers injection
- Human Concern International
- Human-computer interaction (security)
- Human–computer interaction
- Humberside Collegiate Institute
- Huntsman Cancer Institute
- Hwa Chong Institution
- Hydrocarbon indicator
- Hydrogen chloride
- Hyper-converged infrastructure
- What the Bleep Do We Know!?