The structural properties and IR absorption spectra of Pb 4 + substituted Nickel ferrites having general formula Ni 1 + x Pb x Fe 2 - 2 x O 4 (where x=0.0, 0.1, 0.2, 0.3, 0.4 and 0.5) were investigated. Samples of Ni-Pb-Fe system were prepared by the ceramic technique. The X-ray analysis confirmed the single-phase formation of the samples. The lattice parameter was found to increase linearly with composition (x), which is attributed to ionic size difference of cations involved. The X-ray density was also found to increase linearly with composition (x). X-ray intensity ratio calculations show that Pb 4 + occupies A and B sites, which replace Fe 3 + ions and added Ni 2 + ions substitute for B site iron ions.The IR spectra of Ni-Pb ferrite system have been analyzed in the frequency range 200-800 cm - 1 . The IR bands show shift towards the lower frequency side with the addition of Pb 4 + for x=0.0-0.2, which can be attributed to increase in lattice parameter. The bond lengths R A and R B were found to increase with composition (x).