Solid solutions of (1 - x) BaTiO3-xBi(Mg(2/3)Nb(1/)3)O-3 (0 <= x <= 0.6) were prepared via a standard mixed-oxide solid-state sintering route and investigated for potential use in high-temperature capacitor applications. Samples with 0.4 <= x <= 0.6 showed a temperature independent plateau in permittivity (epsilon(r)). Optimum properties were obtained for x = 0.5 which exhibited a broad and stable relative epsilon(r) similar to 940 +/- 15% from similar to 25 degrees C to 550 degrees C with a loss tangent < 0.025 from 74 degrees C to 455 degrees C. The resistivity of samples increased with increasing Bi(Mg2/3Nb1/3)O-3 concentration. The activation energies of the bulk were observed to increase from 1.18 to 2.25 eV with an increase in x from 0 to 0.6. These ceramics exhibited excellent temperature stable dielectric properties and are promising candidates for high-temperature multilayer ceramic capacitors for automotive applications.