We have modelled the full-cycle economics of a green hydrogen value chain to decarbonize trucks. In Europe, at $6/gallon diesel prices, hydrogen trucks will be 30% more expensive in the 2020s. They could be cost-competitive by the 2040s. But the numbers are generous and logistical challenges remain. Green hydrogen trucks will most likely find adoption in niche applications, competing with other technologies, rather than as a wholesale shift to a hydrogen economy.