Two series of tellurite glasses synthesized in a TeO2-WO3-PbO-Na2O-Nb2O5 oxide system with variable contents of WO3 (5÷38mol%) and PbO (0÷18mol%) are designed and manufactured. Their transmission properties, thermal expansion coefficients and glass characteristic temperatures have been determined. The glasses with the highest resistance to recrystallization during thermal treatment have been selected. Fiber drawing tests are performed and confirmation of the usefulness of these out glasses in the manufacture photonic crystal fibers is obtained.