Tellurite glasses are low phonon energy optical materials suitable for the development of optical devices in the near to mid-IR wavelength region. An additional interesting property is their high nonlinearity, which offers the possibility to fabricate specialty core-clad optical fibres for the development of compact supercontinuum sources characterized by high compactness, stability, and efficiency. We will report the recent progress in the development of a new tellurite glass composition with higher mechanical properties, better transparency in the mid-IR and purity in terms of OH- group content. Its thermal and optical properties, including dispersion in the mid-IR, will be illustrated.