A new type of reflectometer has been developed for measuring directional-hemispherical spectral reflectances in the infrared region. The instrument is based upon a cavity-shaped pyroelectric detector that itself collects the radiation reflected by the test sample, thereby obviating the need for an intermediate collector such as an integrating sphere or concave mirror. This detector is made from an electrically polarized plastic film of polyvinyl fluoride, coated with gold-black on its inner surface and backed with brass him on its outer surface in order to provide mechanical strength. The reflectometer has been used with Fourier spectrometer to measure spectral reflectances over the wavelength range 5-30 microm.