Lead-free glasses with a low glass transition temperature, low coefficient of thermal expansion, high fluidity and high durability against water are desirable for sealing of electrical devices. In this study, V2O5, H2WO4, and KPO3, were used to develop a novel sealing glass. We investigated the glass transition temperature, softening temperature, glass crystallization temperature, coefficient of thermal expansion and ratio of weight loss of glasses after waterproof testing. Amorphous glasses were obtained by melting of mixtures of V2O5 (10-60 mol%), H2WO4 (10-50 mol%), and KPO3 (30-70 mol%). Two types of glass (40 mot% V2O5-20 mot% H2WO4-40 mol% KPO3 and 40 mot% V2O5-10 mot% H2WO4-50mol% KPO3) had low glass transition temperature and good fluidity. Addition of Sb2O3 (2.5, 5 or 10 wt%) to the glasses enhanced their durability against water. The coefficient of thermal expansion of the glass composed of 39.0 mol% V2O5-9.7 mol% H2WO4-48.7 mol% KPO3-2.6mol% Sb2O3 was lowered by incorporation of Zr-2(WO4) (PO4)(2), a low-thermal-expansion ceramic filler. The glass showed comparable bonding strength with a commercial lead glass.