Zn2SiO4 ceramics synthesized by the conventional solid-state method exhibited a low Q x f value, possibly due to the formation of a ZnO second phase. However, with a small ZnO reduction from the Zn2SiO4 ceramics, the ZnO second phase disappeared and grain growth occurred due to the formation of a Si-rich liquid phase. Specimens with a large grain size exhibited an improved Q x f value. In particular, the ceramics with nominal composition Zn1.8SiO3.8 sintered at 1300 degrees C exhibited improved microwave dielectric properties of epsilon(r)=6.6, Q x f=147 000 GHz, and tau(f)=-22 ppm/degrees C.