An ultra-broad working temperature dielectric material, BaTiO(3)Na(0.5)Bi(0.5)TiO(3)Nb(2)O(5)MgOGlass with Nd2O3 addition, was investigated for the first time. Microstructure and dielectric properties of the well-sintered samples were studied. XRD results showed the formation of tetragonal perovskite and the presence of a second phase of NaBiTi6O14. It is found that the addition of Nd2O3 produces a decrease in tetragonality of perovskite structure which could be interpreted by the substitution of Nd3+ ions into Ti sites. Bulk densities and dielectric properties were measured as a function of Nd2O3 concentration. The 0.4 mol% Nd2O3-doped sample showed the optimal dielectric performance (epsilon(r) = 1445, tan delta<2.0%, Delta C/C <= +/- 12%) that satisfied EIA-X9R specification. In particular, the ceiling working temperature was significantly enhanced from 200 degrees C to 270 degrees C by doping Nd2O3. Since it possesses large dielectric constant, low dielectric loss, and stable temperature character, this material shows promising applications for the ultra-broad temperature range components, e.g., multilayer ceramic capacitors.