The effects of ZnO additive on the microstructures, the phase formation and the microwave dielectric properties of MgTiO 3 –CaTiO 3 ceramics were investigated. The sintering temperature of ZnO-doped 0.95MgTiO 3 –0.05CaTiO 3 ceramics can be lowered to 1300°C due to the liquid phase effect. Formation of second phase MgTi 2 O 5 can be effectively restrained through the addition of ZnO. The microwave dielectric properties are found strongly correlated with the sintering temperature as well as the amount of ZnO addition. At 1300°C, 0.95MgTiO 3 –0.05CaTiO 3 ceramics with 1wt% ZnO addition possesses a dielectric constant ɛ r of 20, a Q×f value of 65,000 (at 7GHz) and a τ f value of −5.8ppm/°C. In comparison with pure 0.95MgTiO 3 –0.05CaTiO 3 ceramics, the doped sample shows not only a 16% loss reduction but also a lower sintering temperature. That makes it a very promising material to replace the present one for GPS patch antennas.