Accelerating the international use of climate mitigation technologies is key if efforts to curb climate change are to succeed, especially in developing countries, where weak domestic technological innovation systems constrain the uptake of climate change mitigation technologies. Several intergovernmental agencies have set up specific programmes to support the diffusion of climate mitigation technologies. Using a simplified technological innovation system-based framework, this paper aims to systematically review these programmes, with the dual aim of assessing their collective success in promoting technological innovation, and identifying opportunities for the newly formed UNFCCC Technology Mechanism. We conclude that, while all programmes reviewed have promoted technology transfer, they have given limited attention to innovation capabilities with users, government and universities. Functions that could be further developed include knowledge development, legitimation and market formation. These could be focal areas for the UNFCCC Technology Mechanism. We recommend that, in future programmes, part of the funding is dedicated to programmes doing research and development as well as capability development.