Oxygen ion conducting ceramics have been extensively studied due to their characteristic features of mixed charge permeation, high mobility of oxide ion/electrons, structural, phase and thermal stability etc. These are considered to be essential prerequisites for their suitability as electrode materials for solid oxide fuel cell (SOFC), gas sensors and oxygen pumps etc. Modification of structural properties by introducing intrinsic anion deficiency in the lattice structure leading to oxide ion conduction has come in vogue. Such an approach is expected to ensure fast oxygen ion conduction within lattice structure possibly via hopping. However, acceptable O2- ion transport occurs, as per reports in literature, at relatively higher temperature (= 800°C). Literature shows that their structural properties control the electrical conduction and other transport by the lattice defects present (including ionic and electronic defects). Hence, the oxygen vacancy created due to oxygen deficiency ‘d’ is represented by Kröger-Virk relation. Oxygen deficient perovskites (ABO3-d) having Mn at B-site show mixed ionic conduction due to mixed valance states (III/IV). The electric properties become more prominent in nanocrystalline systems where the grain boundary effects play an important role in charge migration. But due to the heterogeneous particle size in nanocrystalline systems, the overall electrical studies suppress the actual grains and grain boundary effect on it. Hence, it is very important to study the ion dynamics and charge transport properties using impedance and modulus spectroscopy. In this paper, we report electrical properties of nanocrystalline BaMnO3-d where, the oxygen deficiency d is created due to presence of mixed oxidation states Mn3+ and Mn4+. The layered hexagonal-cubic crystal structure P63/mmc) of BaMnO3-d as a result of high ionic radii (Ba2+ ~1.35Å) creates hexagonal layer in the system. The electrical properties studied using complex impedance analysis suggests thermally activated charge transport with only bulk contribution up to 300oC beyond which grain boundary effects is prominent. In order to understand the sample electric response in terms of the corresponding electrical equivalent counterpart, the complex impedance and modulus spectrum pattern has been modeled as an equivalent circuit representation in terms of the brick layer model for polycrystalline ceramics. The dc conductivity pattern shows the three regions following mixed conduction behavior at intermediate temperatures. The activation energy at this region >1 eV confirms this behavior.