Polycrystalline ferrites of CdxMg1-xFe2O4 (x = 0, 0.2, 0.4, 0.6, 0.8 and 1.0) with addition of 5% of yttrium has been synthesized by oxalate co-precipitation method and characterized by XRD, SEM and FTIR techniques. The samples were presintered at 700 degrees C for duration of 6 h and sintered at 1050 degrees C for 5 h. The X-ray diffraction measurements confirmed the formation of cubic spinel structure. Lattice constant, X-ray density, physical density, crystallite size, ionic radii on A-site and B-site (r(A), r(B)), bond length on A-site and B-site (A-O, B-O) and porosity have been calculated. The lattice constant is found to increase with increase in Cd2+ content. The physical densities are about 86.96% of their X-ray density. Average crystallite size lies in the range of 28.86-32.06 mm. SEM study shows that the grain size of the samples increases with increase in Cd2+ content. The addition of Y3+ reduces the grain growth. The FTIR spectra shows two strong absorption bands in the frequency range 575-435 cm(-1), on the tetrahedral and octahedral sites, respectively. Further it shows that Y3+ occupies B-sites. (C) 2008 Elsevier B.V. All rights reserved