Room‐temperature interband Faraday rotation has been measured in samples of intrinsic germanium, doped cadmium telluride, and gallium arsenide at 10.59‐&mgr; wavelength, in magnetic fields up to 80 kG. Measurements with a 7‐mm‐diam incident beam indicate that at least 33 dB isolation and a figure of merit exceeding 100 deg/dB should be attainable in a practical device based on either of the first two materials.