The United Nations Framework Convention on Climate Change and the Kyoto Protocol are serviced by the secretariat, also known as the Climate Change Secretariat, whose mandate is laid out in general terms in Article 8 of the Convention.

 The main functions of the secretariat are to:

• make practical arrangements for sessions of the Convention and Protocol bodies
• monitor implementation of the commitments under the Convention and the Protocol through collection, analysis and review of information and data provided by Parties
• assist Parties in implementing their commitments
• support negotiations, including through the provision of substantive analysis
• maintain registries for the issuance of emission credits and for the assigned amounts of emissions of Parties that are traded under emission trading schemes
• provide support to the compliance regime of the Kyoto Protocol
• coordinate with the secretariats of other relevant international bodies, notably the Global Environment Facility (GEF) and its implementing agencies (UNDP, UNEP and the World Bank), the Intergovernmental Panel on Climate Change (IPCC), and other relevant conventions.

Specific tasks include:

• the preparation of official documents for the COP and subsidiary bodies
• the coordination of In-Depth Reviews of Annex I Party national communications
• the compilation of greenhouse gas inventory data.

The growth in technical work needed since the adoption of the Kyoto Protocol (e.g. on reporting guidelines and the LULUCF sector) is leading to a trend of increased technical expertise within the secretariat. 

The secretariat is institutionally linked to the United Nations without being integrated in any programme, and administered under United Nations Rules and Regulations. It now employs some 470 staff, including staff on temporary appointments, from all over the world. Its head, the Executive Secretary, is appointed by the Secretary-General of the United Nations in consultation with the COP through its Bureau, and currently holds the rank of Assistant-Secretary-General. The Executive Secretary reports to the Secretary-General through the Under-Secretary-General heading the Department of Management on administrative and financial matters, and through the Under-Secretary-General heading the Department for Economic and Social Affairs on other matters.

As an impartial body of international civil servants, the secretariat is accountable, through the Executive Secretary, to the COP, CMP and subsidiary bodies and carries out those tasks that fall under its mandate in the Convention and programme budget. The COP, CMP and subsidiary bodies will often request a specific assignment from the secretariat within this mandate, for example, to prepare a background study on a particular issue. The secretariat is guided in its work by the Bureau of the  COP.

Since August 1996, the secretariat has been located in Bonn, Germany. It moved from its previous location in Geneva, Switzerland, following an offer from Germany to host the secretariat, an offer accepted by COP 1.

Every two years, the Executive Secretary proposes a programme budget, setting out the main tasks to be performed by the secretariat in the coming biennium and the funding needed to carry out this work. This proposal is considered in the Subsidiary Body for Implementation (SBI), which then recommends a programme budget for approval by the COP. The Programme Budget is funded by contributions from Parties, their shares being based on the UN scale of assessment.

The secretariat's structure is kept under review to ensure that it responds to the changing needs of the climate change process.