A liquid-hydrogen trailer is a trailer designed to carry cryogenic liquid hydrogen (LH₂) on roads being pulled by a powered vehicle. The largest such vehicles are similar to railroad tanktainers which are also designed to carry liquefied loads. Liquid-hydrogen trailers tend to be large; they are insulated. Some are semi-trailers.^[1]

The U-1 semi-trailer was a liquid-hydrogen trailer designed in the 1950s to carry cryogenic liquid hydrogen (LH₂) on roads being pulled by a powered vehicle. It was constructed by the Cambridge Corporation and had a capacity of 26,000 liters (6,900 U.S. gal; 5,700 imp gal) with a hydrogen loss rate of approximately 2 percent per day. The U-1 was a single-axle semi-trailer. The specifications for its successor the U-2, a double axle semi-trailer, were issued on 15 March 1957.^[2]

Liquid hydrogen trailers are referenced by their size or volume capacity. Liquid-hydrogen trailers typically have capacities ranging from 28,400 to 49,200 liters (7,502 to 12,997 U.S. gal; 6,247 to 10,822 imp gal) gross volume.^{[3] [4]}