Polycrystalline material (Na0.125Bi0.125 Ba0.65Ca0.1)(Nd0.065Ti0.97Nb0.065)O-3 of (Na, Bi and Ca) substituted perovskite compound of Ba(Nd0.1Ti0.8Nb0.1)O-3 was prepared by solid state sintering route. Dielectric measurements (in the temperature range 80-300K) were made on the prepared sample, which reveal the occurrence of diffused dielectric peaks. These peaks are found to be strongly dependent on the frequency of measurement characterizing relaxor behaviour. Modified Arrhenius law was used to characterize the frequency dependence of T-max. Impedance measurements were made on the prepared sample over a wide range of temperature (300-900 K) and frequency (700 Hz-1 MHz), which reveals occurrence of high temperature impedance relaxation with characteristic features similar to that of relaxor materials. An attempt is made to correlate the high temperature impedance relaxation to oxygen vacancy related phenomenon. (c) 2005 Elsevier B.V. All rights reserved.