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. Since the Treaty is not yet in force, the organization is called the Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO).

It was founded in 1996, has over 260 staff from over 70 countries, and is based in Vienna. It is headed by the Executive Secretary, Lassina Zerbo from Burkina Faso. The CTBTO’s main tasks are the promotion of the Treaty and the build-up of the verification regime so that it is operational when the Treaty enters into force.