A facility for measuring the optical properties of solid materials at cryogenic temperatures is being developed at the National Institute of Standards and Technology. A cryostat that houses four bolometric detectors and a six-position sample holder was designed and built. The bolometers operate near 5 K, and the sample temperature can be varied from 6 to 100 K. The beam from a Fourier transform spectrometer is directed to the cryostat by reflective optical components. The measurable wavelengths extend from 1 itm to 1 mm, with appropriate sources and beamsplitters in the spectrometer as well as windows and detectors in the cryostat. The angle of incidence on the sample ranges from 7.5 to 60 ° . The mechanical, electrical, and optical designs are described in this paper. Initial measurement results at wavelengths from 2 to 30 #m and a sample temperature of 10 K are presented.