Abstract Transition metal substituted cobalt nano-ferrites of the formula CoMxFe2−xO4 (M=Cr3+, Ni2+, Cu2+, Zn2+; 0.2≤x≤1.0) have been synthesized via a sol–gel auto-combustion method and their role as novel heterogeneous catalysts in the modified Fenton׳s reaction has been investigated. The entire ferrite compositions are observed to enhance the hydrogen peroxide decomposition reaction, attributed to the cyclic electron transfer process. As the metal concentration is increased, the catalytic activity of the ferrites increases. Interestingly, this is not attributed to the direct participation of the transition metal ion in the cyclic electron transfer. The transition metal ion indirectly influences the catalytic activity by bringing out interesting changes in the cation distribution of the ferrites. The cation distribution of the ferrites is deduced from the values of saturation magnetization using Neel׳s two-sub-lattice model.