| Abbreviation | Description |
| GUAM | Organization for Democracy and Economic Development; acronym for member states - Georgia, Ukraine, Azerbaijan, Moldova |
| GUUAM | acronym for member states - Georgia, Ukraine, Uzbekistan, Azerbaijan, Moldova |
| GWP | gross world product |
| Habitat | United Nations Center for Human Settlements |
| Hazardous Wastes | Basel Convention on the Control of Transboundary Movements of Hazardous Wastes and Their Disposal |
| HF | high-frequency |
| HIV/AIDS | human immunodeficiency virus/acquired immune deficiency syndrome |
| IADB | Inter-American Development Bank |
| IAEA | International Atomic Energy Agency |
| IANA | Internet Assigned Numbers Authority |
| IBEC | International Bank for Economic Cooperation |
| IBRD | International Bank for Reconstruction and Development (World Bank) |
| ICAO | International Civil Aviation Organization |
| ICC | International Chamber of Commerce |
| ICCt | International Criminal Court |
| ICFTU | International Confederation of Free Trade Unions |
| ICJ | International Court of Justice (World Court) |
| ICRC | International Committee of the Red Cross |
| ICRM | International Red Cross and Red Crescent Movement |
| ICSID | International Center for Secretariat of Investment Disputes |
| ICTR | International Criminal Tribunal for Rwanda |
| ICTY | International Criminal Tribunal for the former Yugoslavia |
| IDA | International Development Association |
| IDB | Islamic Development Bank |
| IDP | internally displaced person |
| IEA | International Energy Agency |