Using patent data from 66 countries for the period 1990–2003, we characterize the factors which promote or hinder the international diffusion of climate-friendly technologies on a global scale. Regression results show that technology-specific capabilities of the recipient countries are determinant factors. In contrast, the general level of education is less important. We also show that restrictions to international trade—e.g., high tariff rates—and lax intellectual property regimes negatively influence the international diffusion of patented knowledge. A counter-intuitive result is that barriers to foreign direct investments can promote transfers. We discuss different possible interpretations.