A durable low Tg Sb-stabilized Mo+W phosphate based glass composition exhibiting superior resistance to attack by boiling water, humidity and acids resulting from the addition of Sb to Mo+W phosphate based glass compositions. Specifically, the present invention discloses a glass composition comprising in mol % on the oxide basis, of 0-40% R2O where R includes the alkali metals (Li, Na, K, Rb or Cs) as well as Ag and Tl, 0-20% XO where X includes the alkaline earth metals (Mg, Ca, Sr or Ba) as well as Cu, Zn, Cd and Pb, 15-80% MoO3+WO3, 0.5-60% Sb2O3, and 10-40% P2O5. Additionally, the Sb-stabilized Mo+W phosphate based glass composition can contain a total of 0-5%, in mole percent (mol %) on the oxide basis, of glass forming oxides including, but not limited to, B2O3, Al2O3, SiO2, TeO2, Ga2O3, GeO2, transition metal and rare earth metal oxides, or mixtures thereof. The resulting durable Sb-stabilized Mo+W phosphate based glass compositions are particularly useful as refractory adhesives, sealing glass frits, and overcladding material for glass fiber.