Biofuels are being advocated by certain sections of the commercial aviation industry as a means of reducing greenhouse gas emissions and lowering fossil-fuel dependency within the confines of current aircraft technology and infrastructure. Rising oil prices, increasingly stringent environmental legislation, and continued growth in air travel demand have stimulated the development of renewable lower-carbon fuel alternatives that can act as a substitute for conventional Jet A1 kerosene. However, although biofuels may offer a number of apparent benefits, barriers to widespread commercial uptake and deployment remain, including concerns about competition for feedstocks and impact on global water resources and biodiversity. The processes involved in the uptake of aviation-grade biofuels are not straightforward and there is a need to explore the factors affecting commercial deployment. This paper reports on the findings of a series of in-depth semistructured interviews with key aviation stakeholders in Europe. The research reveals that concerns about the supply of suitable feedstocks, uncertainty surrounding the true life-cycle emissions savings of the fuels, and the perceived lack of policy support are key obstacles that need to be addressed before aviation biofuels can be widely utilized. The research also reveals that the potential inclusion of aviation within the EU Emissions Trading Scheme will create a zero accounting "loophole" for biofuel that may uniquely influence the pattern of uptake in the EU vis-à-vis other world markets. Additional key constraints identified include limitations on the supply of suitable feedstocks, concerns about sustainability of the fuels, and uncertain policy support.