| RIO | Radar Intelligence Officer 
| Others |
| RIO | Radar Intercept Officer
| Others |
| RIO | Radio Information Officer
| Others |
| RIO | Radio Intercept Officer
| Others |
| RIO | Radx Input Output
| Others |
| RIO | Rail Incident Officer
| Others |
| RIO | RAM (Random Access Memory) Input/ Output
| Others |
| RIO | Ram Input Output
| Others |
| RIO | Random Access Memory Input Output
| Others |
| RIO | Rangiora International Office
| Others |
| RIO | Rapid Information Organiser
| Others |
| RIO | Rdf I O
| Others |
| RIO | Re Integrating Offenders
| Others |
| RIO | Re Integration Of Offenders
| Others |
| RIO | Readiness Input And Output
| Others |
| RIO | Real Investment Opportunities
| Others |
| RIO | Really Innovative Original
| Others |
| RIO | Really Interesting Objects
| Others |
| RIO | Realtime Input Output
| Others |
| RIO | Recognition Insight and Openness
| Others |
| RIO | Recognition Insight Openness
| Others |
| RIO | reconfigurable I O
| Others |
| RIO | Reconfigurable Input Output
| Others |
| RIO | Red Iron Oxide
| Others |
| RIO | Reference Identifier Object
| Others |
| RIO | Reference Information Object
| Others |
| RIO | Reference Interconnection Offer
| Others |
| RIO | Reflective Interpolated Optical
| Others |
| RIO | Regional Inspection Officer
| Others |
| RIO | Relation Inherited Object
| Others |
| RIO | Relational Intentional Overflow
| Others |
| RIO | Reliable Innovative and Outstanding
| Others |
| RIO | Remote Infrastructure Operation
| Others |
| RIO | Remote Input Output
| Others |
| RIO | Remote Instant Office
| Others |
| RIO | Reporting Information Online
| Others |
| RIO | Research Ideas and Outcomes
| Others |
| RIO | Research Instruction Online
| Others |
| RIO | Resolution Independent Object
| Others |
| RIO | Resources Input Optimization
| Others |
| RIO | Ressoruces Input Optimisation
| Others |
| RIO | Restoration International Outreach
| Others |
| RIO | Restore Iraqi Oil
| Others |
| RIO | Reusable Information Object
| Others |
| RIO | Review International Organization
| Others |
| RIO | Reviewers International Organization
| Others |
| RIO | Revive International Olympic
| Others |
| RIO | Riada Internet Objects
| Others |
| RIO | Ride It Out
| Others |
| RIO | Right Inferior Oblique
| Others |
| RIO | Rigor in Operations
| Others |
| RIO | Rigorous In Operations
| Others |
| RIO | Rigour In Operations
| Others |
| RIO | Rio De Janeiro International Airport, Rio De Janeiro, Rio de Janeiro, Brazil
| Others |
| RIO | Road Intersection Optimization
| Others |
| RIO | Robot Item Organizer
| Others |
| RIO | Rock In Opposition
| Others |
| RIO | Rowing the Indian Ocean
| Others |