Résumé : Climate change has been identified as one of the most serious global challenges facing the international community in the 21st Century. The European Union (EU) and China are both parties to the UNFCCC and the Kyoto Protocol. Both also recognise climate change as one of the main global challenge they face and both support the UNFCCC as the ultimate framework for international cooperation. Despite common concerns, the EU and China have often appeared to oppose each others in the multilateral negotiations and do not seem to agree upon which foundations to give to the future climate change regime. This was most striking during the catastrophic Copenhagen Summit in December 2009. Parallel to this, however, China and the EU have developed an extensive bilateral cooperation on climate change since 2005, which has been upgraded to the top of their “Comprehensive Strategic Partnership13”. This cooperation, centred on the co-development of clean coal and green technologies, is intended to complement and support the multilateral framework established by the UNFCCC and the Kyoto Protocol.There is indeed a significant difference between arguing of the complementarity of different levels of governance in combating climate change and arguing of the reinforcement of the multilateral negotiation process through bilateral “engagement”. Through this case study, we try first to verify whether such “alliance-building” from bilateral cooperation is observable or not and to sort out the institutional variables that underpin it. Then, we develop some hypothesis to assess whether this bilateral cooperation between strategic partners is indeed a building block or rather a stumbling block to the global effort to combat climate change.