Glass formation was investigated for the Ga2S3-Sb2S3-CsX (X = Cl, Br, I) and Ga2S3-Sb2S3 -AgCI systems. Glasses were obtained for the compositional regions that contain the parts of the lines from the eutectic point of the Ga2S3-Sb2S3 system (20GaS(3/2)center dot 80SbS(3/2)) to the midpoint of the GaS3/2-CsX system (50GaS(3/2)center dot 50CsX), extending to both sides of the lines. The glass transition temperatures were in the range of 210 to 280 degrees C and tended to decrease with increases of the Sb2S3 and CsX contents. Some glasses in these systems had a temperature difference between crystallization and a glass transition of more than 200 K. The infrared transmission limits were located at approximately 14 RM., and the transmission range covered the atmospheric windows. These facts indicate that the glasses are suitable for use as optical materials in infrared optics. Furthermore, the absorption edges at the short wavelength side were blue-shifted, reaching the visible region with the incorporation of CsX. However, glasses in some compositional domains showed inhomogeneous structures in their matrices. Particularly, a unique morphology was observed the inhomogeneous CsCl-incorporated glasses, in which many voids of several micrometers in size were formed. The crystallization behaviors at the borders of the glass forming regions are discussed. (C) 2018 The Ceramic Society of Japan. All rights reserved.