We consider the commitment of large firms with high R&D investments to the development of technologies of climate change mitigation related to the production or storage of energy. We analyse such Climate Change Mitigation Technologies focused on energy production and storage (energy CCMT) across the globe with the aim of assessing whether the Kyoto Protocol fosters the diffusion of inventive activity in energy greentech. Using patents as the key dataset, we give an empirical description of the corporate patenting activity and assess its contribution to the overall energy CCMT inventions across countries and sectors of energy greentech before and after the signing of the Kyoto Protocol (1997). Our observations indicate that climate change issues and greentech development have not been prioritized to the same extent by firms of western countries as opposed to, for example, Japanese firms in the beginning of the 2000s. However, we witness a growing commitment in most of the western countries. US large firms were more prone to gain skills in renewable energy technologies than most of their European counterparts, which continue to heavily invest in traditional energies such as Nuclear energy and Combustion.