Faraday rotation and absorption measurements were made on a bulk single crystal and on evaporated polycrystalline films of EuSe. Bulk EuSe is ferromagnetic, transparent in the red, and exhibits an unusually large Verdet constant at room temperature: -9.7 min/Oe-cm at 6660 Å where the absorption is 173 cm-1. Measurements at 77°K show that the Verdet constant varies approximately inversely with temperature and thereby correlates with the magnetic susceptibility. These properties are due to the Eu + + ion and are comparable to those we have observed in other divalent europium compounds such as Eu2SiO4. The evaporated films of EuSe exhibit a broad but well-defined absorption band at 4600 Å which is essentially duplicated in similarly prepared films of EuS and EuO at 5200 and 5800 Å, respectively. The wavelength dependence of the Faraday rotation of EuSe exhibits a rather complicated structure with two sign reversals in the region of the absorption band. At 6660 Å the Verdet constant measured at room temperature is -6.3 min/Oe-cm agreeing in sign and approximately in magnitude with the bulk value, whereas the maximum value of Verdet constant, +25 min/Oe-cm, occurs at 4330 Å. © 1965 The American Institute of Physics.