The effect of MgO content on the microstructure and microwave dielectric properties of MgO-doped 0.84CaTiO(3)-0.16Sm(0.9)Nd(0.1)AlO(3) ceramics, prepared by solid-state reaction method, was investigated. The permittivity, epsilon(r), of the MgO-doped 0.84CaTiO(3)-0.16Sm(0.9)Nd(0.1)AlO(3) ceramics was about 65, and it decreased slightly with increasing MgO content. And the temperature coefficient of resonant frequency, tau(f) was tuned from +53.3 ppm/degrees C to +26.4 ppm/degrees C as the MgO addition increasing. In addition, it is found that a small amount of MgO could effectively promote the uniformity of the grain morphology, which is beneficial for the improvement of Qxf value. However, grain growth was restrained, and secondary phase MgAl2O4 was observed as MgO content increasing to 0.8 wt%; thus, Qxf value deteriorated seriously. Considering these three parameters of the microwave dielectric properties, the 0.4 wt% MgO-doped 0.84CaTiO(3)-0.16Sm(0.9)Nd(0.1)AlO(3) ceramics exhibited the best performance of epsilon(r)= 64.21, Q x f= 30867 GHz, and tau(f) = 26.4 ppm/degrees C sintered at 1375 degrees C for 3 h. (C) 2014 Elsevier Ltd. All rights reserved.