In this paper, we report on the preparation, dielectric and magnetic properties of Ba5NdNiNb9O30 ceramics and its structural refinement. Ba5NdNiNb9O30 powders were synthesized by solid state reaction at 1350 degrees C for 3 h. X-ray diffraction and Rietveld refinement analysis revealed that the ceramics present a single phase with tetragonal tungsten bronze structure in space group P4bm. Broad dielectric peaks with strong frequency dispersion were observed in the temperature range from 150 to 230 K. The frequency dependence of the dielectric maximum temperature well follows the Vogel-Fulcher relationship and the relaxor behavior can be well fitted with the modified Curie-Weiss law with a diffusivity parameter value of 1.69 at 1 kHz. The temperature dependence of magnetization suggests the absence of a long-range magnetic ordering while a negative paramagnetic temperature theta(Weiss) indicates the presence of weak antiferromagnetic interactions. (C) 2011 Elsevier B.V. All rights reserved.