Current freight transport is highly dependent on fossil fuels and there is a need for a transition to alternative fuels and technologies. Biogas is a type of biofuel that has the potential to reduce climate emissions from freight transport, while providing additional benefits such as recycling of nutrients and increased energy security. This paper uses theories on the diffusion of green technologies to analyse the barriers and drivers for the increased use and diffusion of biogas in freight transport. The empirical focus is on the region of Västra Götaland in Sweden, and qualitative interviews have been conducted with demand-side actors such as transport buyers, haulage companies and vehicle manufacturers. The results confirm the important barriers observed in previous research, such as the higher costs of biogas, financial uncertainties and lack of infrastructure, as well as the interplay between barriers. The main drivers are an increased focus on sustainability both within the sector and from wider society, as well as the environmental properties of biogas. Specific barriers have also been identified such as a fragmented freight market structure with a mix of large and small transport companies, tight profit margins and reduced capacity for investments. There is also a division of labour and responsibilities between transport companies and transport buyers, which makes it unclear who will drive the transition to alternative fuels. In general, the study shows that the different types of uncertainty are perceived by the actors as being a significant barrier that needs to be better conceptualised in diffusion theory.