The optical and magneto‐optical properties of crystals of Hg1−xCdxTe (x=0.37) have been measured over the CO2laser wavelength region. The absorption edge of this composition occurs at about 3.2 &mgr;m, and the Faraday rotation consists of interband and intraband components. The latter is very large inn‐type material due to the small electron effective mass (0.052). The figure of merit ofn‐type material is about 1.0 deg/kOe at 10.6 &mgr;m. Optical‐damage studies give a damage threshold of 160 MW/cm2, indicating application to high‐power laser isolator devices.