Nickel ferrite powders with particle sizes in the 3-5 mu m range have been prepared from coprecipitated nickel-iron oxalate precursors. Firing the nickel-iron oxalate precursor in the range 300-1100 degrees C produced samples of high chemical purity, while introducing significant variations in the distribution of crystallite sizes and surface morphologies. An increase in the powder density from 4.2 to 5.2 g cm(-3) and a decrease in the surface area of the nickel ferrite from 120 to 0.2 m(2) g(-1) were effected by increasing the firing temperature to 1100 degrees C.