Abstract: Spinel ferrites with general formula CdxMg1-xFe2-yCryO4 (x=0,0.2,0.4, 0.6, 0.8, and 1.00; y=0, 0.05 and 0.10) were prepared by standard ceramic method. The observations of variation of dielectric constant and loss tangent is reported in Cr3+ substituted ferrites synthesized by normal solid state reaction method. The formation was confirmed by X-ray diffraction technique. Variation of dielectric constant and loss tangent with substitution was explained on the basis of conduction mechanism.