The influence of Al 3+ substitution on the microstructure and impedance spectroscopy of Ni0.27Cu0.10Zn0.63AlxFe2-xO4 has been studied by scanning electron microscopy and impedance analyzer where the formation of the material in the spinel crystal structure was initially confirmed by X-ray structural analysis with room temperature data. The surface morphology indicates well defined grains separated by grain boundaries and with Al substitution average grain size decrease from 17 μm to 12 μm and zinc losses as well. The complex-plane impedance spectra indicate that the material can be represented by two semicircular arcs (its tendency) which corresponds to the bulk and the grain boundary resistance at high and low frequencies respectively. With Al substitution both grain and grain boundary resistance increases from 7.48 kΩ to 15.62 kΩ and 92.34 kΩ to 192.46 k respectively. Electric modulus spectra reflect the contributions from grain and grain boundary effects: the large resolved semicircle arc caused by the grain effect and the small poorly resolved semicircle arc was attributed to the grain boundary.