This paper critically examines the clean development mechanism (CDM) established under Article 12 of the Kyoto Protocol in terms of its effectiveness as a vehicle for technology transfer to developing countries, a specific commitment under the UNFCCC. Fundamentally, the paper poses the question of whether technology transfer as part of the CDM is a myth or a reality in the broader context of sustainable development. Technology transfer between countries of the North and South is explored in a historical context and the emergence of technology transfer obligations is traced in multilateral environmental agreements. The architecture of the UNFCCC and the Kyoto Protocol are examined in relation to technology transfer obligations. Empirical studies are reviewed to gain an understanding of how CDM operates in practice, with a closer examination of a small number of recent CDM projects. There is an update on the Technology Mechanism being established under the Copenhagen Accord. The paper concludes with a summary of the benefits of CDM to date and its current limitations in achieving the scaling-up of affordable environmentally sound technology transfer envisaged in the Bali Action Plan. The conclusion is that technology transfer must be a much more explicit objective of CDM with better targeting of projects in order to achieve locally sustainable equitable outcomes. Furthermore, the link between CDM and technology transfer needs to be much more explicitly made in order that, in the long run, such interventions will lead to viable low emission development pathways in developing countries.