A study of the magnetic properties of nanoparticulate powders of mixed ferrites prepared by a combustion reaction method is presented. Measurements of the magnetization and of the magnetic susceptibility were carried out for temperature and applied magnetic fields in the ranges of 2–300 K and 85 kOe, respectively. The coercive field was found to be nearly T-independent (11.6–13.7 Oe) cooling the sample from 300 to 2 K. The remanence and the magnetization at the highest applied field were found to increase from 1.6 to 4.5 emu/g and from 58.5 to 105.0 emu/g, respectively, for temperatures in the same range. The values of , and were found to be highly enhanced relative to nondoped samples and samples with higher average particle size.