A new class of I.R. transmitting glasses have been discovered in the binary systems Te-Cl and Te-Br and in the ternary systems Te-Cl-S, Te-Cl-Se, Te-Br-S, Te-Br-Se, Te-I-Se. The ternary glasses have a very high resistance towards devitrification. The glass temperature Tg is ranging from 50 to 80° C depending on the composition. The S or Cl containing glasses have their I.R. edge located in the 13 pm region while the compositions not containing those light elements have their multiphonon edge near 20 μm. A typical glass composition such as Te3Br2Se has a potential high transparency of about 10 dB/km at 10.6 μm estimated from band-gap and multiphonon absorption. Samples prepared from high purity compounds show no parasitic absorption bands due to OH, SH, and so on.