Most of the projections of the cost of meeting climate change mitigation targets hinge crucially upon assumptions made about the cost and timing of the development of breakthrough technologies. However, very little is known about the conditions which are likely to give rise to breakthrough technologies. This paper seeks to uncover attributes of inventions - as reflected in patent data - which serve as "leading indicators" of subsequent technological and market development in climate change mitigation technologies. The role of industrial generality emerges as being robustly correlated with subsequent technological diffusion, whether measured as subsequent patent counts, commercial applicability, or attractiveness to risk finance. The indicator of closeness to science shows also a positive association with later technological diffusion. Originality and radicalness have more ambiguous results. This work can be seen as a foundation for the future development of a methodology providing guidance to policymakers in the choices made with respect to public support for different technological fields.