The effect of cyclotron resonance on the detection of microwave radiation by a glow discharge tube has been investigated. This effect was reported about a decade ago for the detection of 70‐GHz millimeter‐wave radiation using a magnetic field of 26 kG. In the present work a similar experiment has been carried out with 9.1‐GHz microwave radiation a resonance in the detection signal at a magnetic field of 3.1 kG has been found. This experiment, which involves the use of an X‐band microwave source, a moderate magnetic field, and the plasma of a simple glow discharge tube, can easily be adopted in a physics student laboratory.