B2O3 was added to nominal composition Zn1.8SiO3.8 (ZS) ceramics to decrease their sintering temperature for application to low-temperature cofired ceramic (LTCC) devices. B2O3 reacted with SiO2 to form a liquid phase containing SiO2 and B2O3. The composition and melting temperature of the liquid phase depended on the sintering temperature and the B2O3 content. The specimen containing 20.0 mol% of B2O3 sintered at 900 degrees C exhibited high microwave dielectric properties of Q x f=53 000 GHz, epsilon(r)=5.7, and tau(f)=-16 ppm/degrees C, confirming the promising potential of the B2O3-added ZS ceramics as candidate materials for the LTCC devices.