Decommissioning or decommissioned may refer to:
Infrastructure
- Nuclear decommissioning, the process of closing a nuclear facility
- Decommissioned highway, a disused road or one removed of numbered highway status
- Greenfield status, a decommissioned industrial site considered back to its pre-establishment condition
- Base Realignment and Closure of US military bases
Military
- Ship decommissioning
- Ship-Submarine Recycling Program, a U.S. Navy process for decommissioning nuclear vessels
- Demobilization, decommissioning of military personnel
- Disarmament
- Decommissioning in Northern Ireland, disarmament as part of that country's peace process circa 1998–2001
- Decommissioning pennant, a type of naval flag