This paper elaborates an empirical analysis of the temporal and geographical distribution of green technology, and on how specific country characteristics enable or thwart environmental inventive activities. Using patent data on 63 countries over the period 1971–2012 we identify key drivers of cross-country diversification and specialisation. Our first finding is that countries diversify towards green technologies that are related to their existing competences. Notably, the degree of green technology maturity matters more than a country`s level of development. The second main result is that countries move along cumulative paths of specialisation, and towards more mature green technologies. Interestingly, the complexity of green technologies is not an obstacle to further specialisation. This holds also for developing countries that are most exposed to climate change hazards.