Abstract Glass formation has been investigated in the Sb 2O 3–ZnBr 2 binary system. Vitreous samples have been obtained for batches containing 20–90 mol% Sb 2O 3. Chemical analysis shows that bromine concentration is smaller than expected and real compositions belong to the Sb 2O 3–ZnBr 2–ZnO ternary system. However, the discrepancy between nominal and analyzed compositions is fair for Sb 2O 3 content larger than 50 mol%. Optical transmission lies between 400 nm and 7 μm and refractive index ranges from 2.0 to 2.1. Glass transition occurs around 300 °C, and crystallization exotherm does not appear in the differential scanning calorimetry scan at 10 K s −1 for samples containing 50–60 mol% Sb 2O 3. Thermal expansion varies between 120 and 220×10 −7 K −1 as antimony content decreases. Microhardness is close to 200 kg/mm 2. These glasses have low phonon energy and make potential materials for infrared transmission and active fibers.