Encouraging collaboration on technology development is particularly pertinent when addressing public bads such as global climate change or regional water pollution. Importantly, international collaboration in research and technology can help local businesses take advantage of existing technologies (i.e. help build local absorptive capacity). This, in turn, helps increase the uptake of cleaner technologies globally. Inventors seek protection for their inventions in countries where they expect to invest, export or otherwise market their products. Often they do so in multiple jurisdictions (geographic markets). Patent data present a number of attractive properties compared to other alternative metrics of innovation. They are widely available, quantitative, commensurable and outputoriented. They can also be disaggregated - an important advantage when analysing environment-related technologies. At the same time, not all innovations or inventions are patented. Further, the number of patents by itself does not indicate their relative importance and impact. Analytical techniques have been developed to overcome some of these limitations (e.g. patent family size, relative technological advantage). Yet it is important to carefully interpret these indicators.