An evanescent wave leaks out of an unclad optical fiber and it can be absorbed in samples that are in close proximity to the fiber. Information about the characteristic absorption lines of these samples may be obtained from measurements of the transmission of the fiber as a function of wavelength. The resulting Fiberoptic Evanescent Wave Spectroscopy (FEWS) may then be used for studying samples in contact with the fibers. FEWS has already been performed in the visible and in the UV, using silica fibers. It is possible now to extend the spectral range to the mid and far IR, using FTIR spectrometers in conjunction with IR transmitting fibers that are placed inside the spectrometers or externally. This gives rise to a novel family of fiberoptic chemical sensors that are selective, sensitive and fast.