A comparative study of manganese ferrites containing cadmium and zinc, with and without magnesium additions, was performed in order to estimate the effect of cadmium on square-loop magnetic properties. The preparation of cadmium ferrites is very complicated because of the detrimental cadmium volatilization. This may be reduced by applying high oxygen pressure at peak sintering temperature. Ferrites containing cadmium have relatively lower coercive force than those containing zinc. The gain in magnetic properties is primarily due to crystal growth favoured by the presence of cadmium in the solid-state reaction of oxides.