The effects of Co2O3 addition on the sintering behavior, phase formation, microstructure and microwave dielectric properties of 0.95MgTiO(3)-0.05CaTiO(3) ceramics have been investigated. The structure and microstructure of the ceramics were investigated using X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy. These results suggested that Co2O3 addition not only contributes in lowering the sintering temperature but also inhibits the formation of second phase MgTi2O5 in 0.95MgTiO(3)-0.05CaTiO(3) ceramics. Moreover, the decomposition of Co2O3 would inhibit the Ti4+ from being restored to Ti3+, which had the positive effect on the Q x f value. A fine combination of microwave dielectric properties (epsilon (r) = 20.48, Q x f = 76,485 GHz, tau (f) = 2.43 ppm/A degrees C) was achieved for 0.95MgTiO(3)-0.05CaTiO(3)-0.01Co(2)O(3) ceramics sintered at 1300 A degrees C for 4 h, which satisfied microwave applications in resonators, filters and antenna substrates.