A cryogenic liquid expansion turbine has a turbine wheel (6) mounted on a rotary shaft (8), at least one radial inlet (12) for cryogenic liquid to be expanded in the expansion turbine (20, 22) for the rotary shaft, and a dry gas sealing means (30) at a position along the rotary shaft (8) between the turbine wheel (6) and the bearings (20 and 22). There is a thermal barrier member (70) between the turbine wheel (6) and the dry gas sealing means (30), a gas chamber (76) on the dry gas sealing means (30)- side of the thermal barrier member (70), and an inlet (78) for cryogenic gas to the said gas chamber (76).