Ferrites which general formula is (M(X)+2O)(M(Y)2+3O3) and with M(X) and M(Y) = Fe in the case of magnetite, can generate multiple compounds with enhanced properties by substation of M(X) for Co, Ni, Mn, etc. with different properties. In particular, properties of manganese ferrites arise from the distribution of cations (Mn+2 and Fe+3) in the tetrahedral and octahedral sites. In fact, saturation magnetization of a spinel ferrite depends strongly on the composition, particle size and Fe-Mn distribution.We propose to investigate the spinel structure (percentage in the tetrahedral and octahedral sites), oxygen stoichiometry and magnetic. Besides, exchange of cations between tetrahedral and octahedral sites when sample is heating the first time is proposed.