The microwave dielectric properties of (1 - x)CaTiO3-xNd(Mg1/2Ti1/2)O-3 (0.1 <= x <= 1.0) ceramics prepared by the conventional solid state method have been investigated. The system forms a solid solution throughout the entire compositional range. The dielectric constant decreases from 152 to 27 as x varies from 0.1 to 1.0. In the (1 -x)CaTiO3-xNd(Mg1/2Ti1/2)O-3 system, the microwave dielectric properties can be effectively controlled by varying the x value. At 1400 degrees C, 0.1 CaTiO3-0.9M(Mg1/2Ti1/2)O-3 has a dielectric constant (epsilon(r)) of 42, a Q xf value of 35 000 GHz and a temperature coefficient of resonant frequency (tau(f)) of - 10 ppm/degrees C. As the content of Nd(Mg1/2Ti1/2)O-3 increases, the highest Q x f value of 43 000 GHz for x = 0.9 is achieved at the sintering temperature 1500 degrees C. (C) 2005 Elsevier Ltd. All rights reserved.