| HDO | Hacker's Diet Online 
| Others |
| HDO | Hamdam Development Organization
| Others |
| HDO | Hard Disk Only
| Others |
| HDO | Hardware Design Online
| Others |
| HDO | Haystack Distribution of OpenTag
| Others |
| HDO | Health Delivery Organization
| Others |
| HDO | Healthcare Discount Organization
| Others |
| HDO | Hearing Designation Order
| Others |
| HDO | Heavy Diesel Oil
| Others |
| HDO | Heavy Duty Oil
| Others |
| HDO | High Definition OLED
| Others |
| HDO | High Definition Optics
| Others |
| HDO | High Definition Oscilloscope
| Others |
| HDO | High Definition Oscilloscopes
| Others |
| HDO | High Density Overlaid
| Others |
| HDO | High Density Overlay
| Others |
| HDO | Highly Distributed Organisation
| Others |
| HDO | Hilversumsche Draadlooze Omroep
| Others |
| HDO | Hispanic Democratic Organization
| Others |
| HDO | Histograms Of Dominant Orientations
| Others |
| HDO | Hokage Dot Org
| Others |
| HDO | Hondo Municipal Airport, Hondo, Texas USA
| Others |
| HDO | Human Development Organisation
| Others |
| HDO | Human Development Organization
| Others |
| HDO | Human Dimensions of Organizations
| Others |
| HDO | Humanitarian Demining Operations
| Others |
| HDO | Hunky Dory Organization
| Others |
| HDO | Hypothetical Development Organization
| Others |