CaTi1-x(Fe0.5Nb0.5)(x)O-3 (0 <= X <= 1) dielectrics were synthesized via the solid state reaction route and structure analysis was performed together with the dielectric characterization. The substitution of Ti4+ by Fe3+/Nb5+ and developed phase were studied by X-ray diffraction. The dielectric constant and temperature coefficient of resonant frequency decrease rapidly with an increase of x. The influence of 1-5 wt.% B2O3 as a sintering additive investigated at CaTi0.5(Fe0.5Nb0.5)(0.5)O-3 solid solutions. The dielectric properties were found to strongly depend on the sintering conditions and contents of B2O3 additions. epsilon(r) = 52.3, Q x f(o) = 2930 GHz and T-f = 13 ppm/degrees C were obtained for CaTi0.5(Fe0.5M0.5)(0.5)O-3 specimen 3 wt.% B2O3 sintered at 900 degrees C for 2 h. (C) 2006 Elsevier Ltd. All rights reserved.