The change in the absorption loss of IR-transmitting chalcogenide glass fibers in the temperature range of -90 degrees C <or= T <or= 70 degrees C was investigated. For sulfur-based glass fibers the change in loss relative to room temperature was slightly affected by the temperature in the wavelength region of 1-5 microm. For lambda >or= 6 microm the change in loss was mainly due to multiphonon absorption. The change in loss for tellurium-based glass fibers increased significantly at T = 60 degrees C. The increase in the loss at short wavelengths (lambda <or= 4.1 microm) was due to electronic excitations in the tail states. Between 5 and 9 microm there was noticeable free-carrier absorption. Beyond lambda >or= 9 microm, multiphonon absorption dominated the loss spectrum.