Zinc aluminate (ZnAl2O4) and bismuth substituted zinc aluminate (ZnAl1.9Bi0.1O4) compounds of nano size were synthesized by co-precipitation method using ammonia as the precipitating agent. The synthesized compounds were characterized by Powder X-ray diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR), Scanning Electron microscopy (SEM). The average crystallite size of the sample varied from 5.5 to 5.1 nm. Influence of bismuth substitution on the dielectric constant and dielectric loss of zinc aluminate was studied at room temperature as a function of frequency (10 Hz-5 KHz). These studies suggest that dielectric dispersion was due to Maxwell-Wagner Interfacial Polarization. Variation in dielectric constant and dielectric loss was noticed with the substitution of bismuth in zinc aluminate. © 2015, Sphinx Knowledge House. All rights reserved.