TeO 2-based glasses have extremely high refractive indices up to 2.30. In this paper are presented glass formation areas, crystallization ability, optical parameters and physical properties of glasses in the systems TeO 2–WO 3–Bi 2O 3 and TeO 2–WO 3–PbO. The structure of the glasses was studied by means of IR spectroscopy. Values of the magneto–optical parameter of the same glasses (the Verdet constant) are also given.