Abstract: The present disclosure refers to a method and an apparatus for cryogen-free concentration of a hyperpolarized noble gas in a continuously flowing stream of gas. The method comprises the following steps: providing a mixture of gases containing hyperpolarized noble gas and at least one process gas; passing the prepared gas mixture as a continuously flowing stream of gas through a gas separation device with a semipermeable membrane in order to separate the gases; and concentrating the hyperpolarized noble gas in the gas separation device, in which at least part of the at least one process gas or the hyperpolarized noble gas is separated from the continuously flowing stream of gas by means of the semipermeable membrane. It also provides for the use of a continuous stream of gas with concentrated hyperpolarized noble gas for magnetic resonance spectroscopy or magnetic resonance tomography.