The Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) is an international organization that will be established upon the entry into force of the Comprehensive Nuclear-Test-Ban Treaty, a Convention that outlaws nuclear test explosions. Its seat will be Vienna, Austria. The organization will be tasked with verifying the ban on nuclear tests and will operate therefore a worldwide monitoring system and may conduct on site inspections. The Preparatory Commission for the CTBTO, and its Provisional Technical Secretariat, were established in 1997 and are headquartered in Vienna, Austria.

The Comprehensive Nuclear-Test-Ban Treaty will enter into force 180 days after the Treaty has been ratified by 44 States, listed in Annex 2 of the Treaty, which were designated to have a nuclear reactor or at least some advanced level of nuclear technology. As of December 2011, 41 of these Annex 2 states have signed the treaty and 36 have ratified. India, North Korea and Pakistan have not signed or ratified the treaty; China, Egypt, Iran, Israel and the United States have signed but have not ratified.