We measured the spatial distribution of microwave fields and dissipative surface currents in various passive and active superconducting thin‐film devices during their operation at a temperature of about 4 K. We used low‐temperature scanning electron microscopy which offers a spatial resolution of about 1 &mgr;m and we present sample response models for interpreting the imaging results. Such investigations may have important consequences for the improvement of the design and preparation of superconducting thin‐film microwave devices. ©1996 American Institute of Physics.