A compressor unit including a centrifugal compressor for compressing a gas and an electric motor with a stator and a rotor for driving the compressor. The compressor and the electric motor are accommodated in a common gastight housing, provided with a gas inlet and a gas outlet.The stator is accommodated in a separate stator space which is delimited by a wall section, surrounding the stator, of the housing, a gastight partition which extends freely between the stator and the rotor of the electric motor, and at least one end wall which extends between the partition and the housing of the compressor unit.The partition is of a material of such high strength that it remains clear of the stator and the rotor under working pressures of the gas.