| HCO | Haitian Christian Outreach 
| Others |
| HCO | Hallock Municipal Airport, Hallock, Minnesota USA
| Others |
| HCO | Halogen Convection Oven
| Others |
| HCO | Handling Control Officer
| Others |
| HCO | Harassment Contact Officer
| Others |
| HCO | Harmful Content Ontology
| Others |
| HCO | Harvard College Observatory
| Others |
| HCO | HCA Credentialing Online
| Others |
| HCO | Head of Contracting Office
| Others |
| HCO | Health Care Official
| Others |
| HCO | Health Care Options
| Others |
| HCO | Health Care Organization
| Others |
| HCO | Health care organizations
| Others |
| HCO | Health Careers Orientation
| Others |
| HCO | Health Concerned Organization
| Others |
| HCO | Health Credit Outcome
| Others |
| HCO | Healthcare Communicators of Oregon
| Others |
| HCO | Healthcare Community Online
| Others |
| HCO | Hearing Carry Over
| Others |
| HCO | Hearing carry-over
| Others |
| HCO | Heavy Cycle Oil
| Others |
| HCO | Helicopter Control Officer
| Others |
| HCO | Helping Companies Operate
| Others |
| HCO | Hernandez & Company, CPAs
| Others |
| HCO | Heva Clonia Online
| Others |
| HCO | High Cab Over Engine
| Others |
| HCO | High Capacity Output
| Others |
| HCO | Hill Climb Optimization
| Others |
| HCO | Hmong Culture Outreach
| Others |
| HCO | Hollister Company
| Others |
| HCO | Home and Community Options
| Others |
| HCO | Home Counselor Online
| Others |
| HCO | Honor Code Office
| Others |
| HCO | Html Converter
| Others |
| HCO | Hubbard Communication Office
| Others |
| HCO | Hubbard Communications Office
| Others |
| HCO | Humming Bird Cyber Olympiad
| Others |
| HCO | Hydraulic Clearance Optimization
| Others |
| HCO | Hydrogen Carbon and Oxygen
| Others |
| HCO | Hyperconverged Cluster Operator
| Others |
| HCO | Hyundai Club of Ontario
| Others |