The positions of the metal ions in the spinel-type structures of compds. of the type MntFe3-tO4 in the region 0.25 <t <1.50 were detd. by the method of Skolnick, et al., (CA 52, 9750h) which employs the diffraction of x-rays of different wavelengths. After a single-phase spinel has been formed by solid-state reaction of Mn and Fe oxide mixts., a change in the distribution of cations during heating still occurs. The time needed for reaching the equil. state of the distribution of cations depends on the compn. The final structure of samples quenched from 1000 Deg and from 1400 Deg, both with the compn. MnFe2O4, is different. The relation between position and valence of the cations is discussed.