A role of Al substitution in variation of magnetic properties of NiFe2O4 is studied. The confirmation of single phase spinel structure and the evaluation of lattice constant have been worked out from X-ray powder data and location of band position has been studied using IR spectra of the present series. Lattice constant and Curie temperature decreases as Al3+ content goes on increasing. (c) 2005 Published by Elsevier B.V.