An apparatus for producing a nuclear spin-polarized noble gas by spin-polarizing a noble gas in the presence of an optical pumping catalyst under application of magnetic field and laser light, including a cell having a thin reaction chamber, a gas introduction conduit connected in fluid communication with the reaction chamber for feeding the noble gas, a gas discharge conduit connected in fluid communication with the reaction chamber, a first gate valve having an outlet port connected to the gas introduction conduit and an inlet port adapted to be in fluid communication with a noble gas introduction line, a second gate valve having an inlet port connected to the gas discharge conduit and an outlet port, and a capillary tube removably connected to the outlet port of the second valve for recovering a nuclear spin-polarized noble gas produced in the reaction chamber. The apparatus may be directly connected to NMR or MRI.